Philosophically, God's existence is something that is reasoned to (as with all other propositions whatever, as well). In a larger epistemology, including religious faith, it is not. I would argue that man is inherently religious (anthropology easily bears this out), so that the religious impulse must be stifled in an atheist. It is already there.
My comprehension of God comes from the deeply felt conviction of a superior intelligence that reveals itself in the knowable world. In common terms, one can describe it as 'pantheistic' (Spinoza).
(Answer to the question, "What is your understanding of God?" Kaizo, 5, no. 2, 1923, 197; in Alice Calaprice, editor, The Expanded Quotable Einstein, Princeton University Press, 2000, 203)
Now, I would ask an atheist: whence comes Einstein's "deeply felt conviction"? Is it a philosophical reason or the end result of a syllogism? He simply has it. It is an intuitive or instinctive feeling or "knowledge" or "sense of wonder at the incredible, mind-boggling marvels of the universe". Atheists don't possess this intuition, but my point is that it is not utterly implausible or unable to be held by even the most rigorous, "non-dogmatic" intellects, such as Einstein and Hume. And the atheist has to account for that fact somehow, it seems to me.
Einstein in 1921 [source]
My religiosity consists of a humble admiration of the infinitely superior spirit that reveals itself in the little that we can comprehend about the knowable world. That deeply emotional conviction of the presence of a superior reasoning power, which is revealed in the incomprehensible universe, forms my idea of God.
(Calaprice, ibid., 204 / To a banker in Colorado, 1927. Einstein Archive 48-380; also quoted in Helen Dukas and Banesh Hoffmann, Albert Einstein, the Human Side [Princeton Univ. Press, 1981], 66, and in the New York Times obituary, April 19, 1955)
I believe in Spinoza's God who reveals himself in the harmony of all that exists, but not in a God who concerns himself with the fate and actions of human beings.
(Ibid., 204 / Telegram to a Jewish newspaper, 1929; to Rabbi Herbert S. Goldstein of the Institutional Synagogue in New York . Einstein Archive 33-272)
What do atheists think Einstein meant here when he used the word "believe"? Do they think he had an elaborate argument that ended in his conclusion: "I believe in Spinoza's God"?
I am of the opinion that all the finer speculations in the realm of science spring from a deep religious feeling.
(Calaprice, ibid., 206 / Forum and Century 83, 1930, 373)
What does Einstein mean by "deep religious feeling"? Is this a philosophical and/or demonstrable or provable concept? Or is it more like an intuition? How can it be epistemically justified? How can a man like Einstein hold such a view in the first place, according to the atheist? Perhaps he himself provides an answer of sorts:
It is very difficult to elucidate this [cosmic religious] feeling to anyone who is entirely without it . . . In my view, it is the most important function of art and science to awaken this feeling and keep it alive in those who are receptive to it.
(Calaprice, ibid., 207 / Cosmic Religion, 1931, 48-49)
In what way would an atheist think Einstein would say such people are "deficient"? He denies that a personal God put this knowledge in people, yet on the other hand he clearly assumes it is innate, normal, and self-evident. How can he do that?
[T]he belief in the existence of basic all-embracing laws in Nature also rests on a sort of faith. All the same this faith has been largely justified so far by the success of scientific research. But, on the other hand, everyone who is seriously involved in the pursuit of science becomes convinced that a spirit is manifest in the laws of the universe -- a spirit vastly superior to that of man, and one in the face of which we with our modest powers must feel humble. In this way the pursuit of science leads to a religious feeling of a special sort, which is indeed quite different from the religiosity of someone more naive.
(To student Phyllis Right, who asked if scientists pray, January 24, 1936. Einstein Archive 42-601, 52-337; from Dukas and Hoffman, ibid., pp. 32-33)
At first, then, instead of asking what religion is I should prefer to ask what characterizes the aspirations of a person who gives me the impression of being religious: a person who is religiously enlightened appears to me to be one who has, to the best of his ability, liberated himself from the fetters of his selfish desires and is preoccupied with thoughts, feelings and aspirations to which he clings because of their super-personal value . . . Accordingly a religious person is devout in the sense that he has no doubt of the significance of those super-personal objects and goals which neither require nor are capable of rational foundation . . . If one conceives of religion and science according to these definitions then a conflict between them appears impossible. For science can only ascertain what is, but not what should be, and outside of its domain value judgments of all kinds remain necessary. . . . Now, even though the realms of religion and science in themselves are clearly marked off from each other, nevertheless there exist between the two strong reciprocal relationships and dependencies . . . science can only be created by those who are thoroughly imbued with the aspiration toward truth and understanding. This source of feeling, however, springs from the sphere of religion. To this there also belongs the faith in the possibility that the regulations valid for the world of existence are rational, that is, comprehensible to reason. I cannot conceive of a genuine scientist without that profound faith. The situation may be expressed by an image: science without religion is lame, religion without science is blind. . . . a legitimate conflict between science and religion cannot exist. . . . But whoever has undergone the intense experience of successful advances made in this domain is moved by profound reverence for the rationality made manifest in existence. By way of the understanding he achieves a far-reaching emancipation from the shackles of personal hopes and desires, and thereby attains that humble attitude of mind toward the grandeur of reason incarnate in existence, and which, in its profoundest depths, is inaccessible to man. This attitude, however, appears to me to be religious, in the highest sense of the word.
("Science and Religion": Address at the Conference on Science, Philosophy, and Religion in Their Relation to the Democratic Way of Life, New York, 1940; in Ideas and Opinions [Crown: New York, 1954, 1982], p. 46; also published in Nature, 146: 605-607  )
In view of such harmony in the cosmos which I, with my limited human mind, am able to recognize, there are yet people who say there is no God. But what makes me really angry is that they quote me for support of such views.
(Ibid., 214 / reply to German anti-Nazi diplomat and author Hubertus zu Lowenstein around 1941. Quoted in the latter's book, Towards the Further Shore, London, 1968, 156)
Then there are the fanatical atheists whose intolerance is the same as that of the religious fanatics, and it springs from the same source . . . They are creatures who can't hear the music of the spheres.
(Ibid., 214 / 7 August 1941. Einstein Archive 54-297)
I have found no better expression than 'religious' for confidence in the rational nature of reality, insofar as it is accessible to human reason. Whenever this feeling is absent, science degenerates into uninspired empiricism.
(Ibid., 216 / To Maurice Solovine, 1 January 1951. Einstein Archive 21-474; published in Letters to Solovine, 119)
The bigotry of the nonbeliever is for me nearly as funny as the bigotry of the believer.
(quoted in Robert N. Goldman, Einstein's God: Albert Einstein's Quest as a Scientist and as a Jew to Replace a Forsaken God [Jason Aronson: 1997] )
Many similar utterances of Einstein can be found:
I do not believe in a personal God and I have never denied this but have expressed it clearly. If something is in me which can be called religious then it is the unbounded admiration for the structure of the world so far as our science can reveal it.
(Letter to an atheist [24 March 1954] as quoted in Albert Einstein: The Human Side [Princeton University Press: 1981], edited by Helen Dukas and Banesh Hoffman, p. 43)
I'm not an atheist and I don't think I can call myself a pantheist. We are in the position of a little child entering a huge library filled with books in many different languages. The child knows someone must have written those books. It does not know how. The child dimly suspects a mysterious order in the arrangement of the books but doesn't know what it is. That, it seems to me, is the attitude of even the most intelligent human being toward God. We see a universe marvelously arranged and obeying certain laws, but only dimly understand these laws. Our limited minds cannot grasp the mysterious force that moves the constellations.
(From an interview, quoted in Glimpses of the Great by G. S. Viereck [Macauley, New York, 1930], cited in Max Jammer, Einstein and Religion: Physics and Theology [Princeton University Press, 1999], p. 48)I have repeatedly said that in my opinion the idea of a personal God is a childlike one. You may call me an agnostic, but I do not share the crusading spirit of the professional atheist whose fervor is mostly due to a painful act of liberation from the fetters of religious indoctrination received in youth. I prefer an attitude of humility corresponding to the weakness of our intellectual understanding of nature and of our own being.
(Letter to Guy H. Raner Jr., 28 September 1949, quoted by Michael R. Gilmore in Skeptic, Vol. 5, No. 2)Try and penetrate with our limited means the secrets of nature and you will find that, behind all the discernible concatenations, there remains something subtle, intangible and inexplicable. Veneration for this force beyond anything that we can comprehend is my religion. To that extent I am, in point of fact, religious.
(Response to atheist, Alfred Kerr [Winter 1927] who after deriding ideas of God and religion at a dinner party in the home of the publisher Samuel Fischer, had queried him "I hear that you are supposed to be deeply religious" -- as quoted in Diaries of a Cosmopolitan: Count Harry Kessler, 1918-1937, by H. G. Kessler, [Littlehampton Book Services Ltd, 1971 edition] )The fairest thing we can experience is the mysterious. It is the fundamental emotion which stands at the cradle of true art and true science. He who knows it not and can no longer wonder, no longer feel amazement, is as good as dead, a snuffed-out candle. It was the experience of mystery -- even if mixed with fear -- that engendered religion. A knowledge of the existence of something we cannot penetrate, of the manifestations of the profoundest reason and the most radiant beauty, which are only accessible to our reason in their most elementary forms -- it is this knowledge and this emotion that constitute the truly religious attitude; in this sense, and this sense alone, I am a deeply religious man. . . . Enough for me the mystery of the eternity of life, and the inkling of the marvellous structure of reality, together with the single-hearted endeavour to comprehend a portion, be it ever so tiny, of the reason that manifests itself in nature.(in The World As I See It , reprinted in 2007 [Filiquarian Publishing], pp. 14-15; originally from What I Believe, 1930; different translation cited in Jammer, ibid., p. 73)[C]osmic religious feeling is the strongest and noblest incitement to scientific research. Only those who realize the immense efforts and, above all, the devotion which pioneer work in theoretical science demands, can grasp the strength of the emotion out of which alone such work, remote as it is from the immediate realities of life, can issue. What a deep conviction of the rationality of the universe, and what a yearning to understand, were it but a feeble reflection of the mind revealed in this world, Kepler [Lutheran] and Newton [Arian theist] must have had to enable them to spend years of solitary labour in disentangling the principles of celestial mechanics! . . . Only one who has devoted his life to similar ends can have a vivid realization of what has inspired these men and given them the strength to remain true to their purpose in spite of countless failures. It is cosmic religious feeling that gives a man strength of this sort. A contemporary has said, not unjustly, that in this materialistic age of ours the serious scientific workers are the only profoundly religious people.
You will hardly find one among the profounder sort of scientific minds without a peculiar religious feeling of his own.
(Ibid., p. 37; from his essay, "Religion and Science," New York Times Magazine, Fall 1930, section 5, pages 1-2)
The men who have laid the foundations of physics on which I have been able to construct my theory are Galileo, Newton, Maxwell, and Lorentz.
(Interview with The New York Times, 2 April 1921; cited in Max Jammer, Einstein and Religion: Physics and Theology [Princeton University Press, 1999], p. 35)Speaking of the spirit that informs modern scientific investigations, I am of the opinion that all the finer speculations in the realm of science spring from a deep religious feeling, and that without such feeling they would not be fruitful.
(conversation with J. Murray, early in 1930 in Berlin, in Jammer, ibid., pp. 68-69)
I am enough of an artist to draw freely upon my imagination. Imagination is more important than knowledge. Knowledge is limited. Imagination encircles the world.
("What Life Means to Einstein": Interview with George Sylvester Viereck, The Saturday Evening Post [26 October 1929, p. 17] )
As a child I received instruction both in the Bible and in the Talmud. I am a Jew, but I am enthralled by the luminous figure of the Nazarene. . . . Jesus is too colossal for the pen of phrasemongers, however artful. No man can dispose of Christianity with a bon mot. . . . No one can read the Gospels without feeling the actual presence of Jesus. His personality pulsates in every word. No myth is filled with such life. How different, for instance, is the impression which we receive from an account of legendary heroes of antiquity like Theseus. Theseus and other heroes of his type lack the authentic vitality of Jesus. . . . No man can deny the fact that Jesus existed, nor that his sayings are beautiful. Even if some them have been said before, no one has expressed them so divinely as he.
(Interview with George Sylvester Viereck, 26 October 1929; see also Denis Brian, Einstein — A Life [John Wiley & Sons, Inc., New York, 1996], pp. 277-278)
What separates me from most so-called atheists is a feeling of utter humility toward the unattainable secrets of the harmony of the cosmos.
("Einstein and Faith," Time Magazine, 5 April 2007)
The fanatical atheists are like slaves who are still feeling the weight of their chains which they have thrown off after hard struggle. They are creatures who--in their grudge against traditional religion as the "opium of the masses"-- cannot hear the music of the spheres.
("Einstein and Faith," Time Magazine, 5 April 2007)It is true that convictions can best be supported with experience and clear thinking. On this point one must agree unreservedly with the extreme rationalist. The weak point of his conception is, however, this, that those convictions which are necessary and determinant for our conduct and judgments cannot be found solely along this solid scientific way.
For the scientific method can teach us nothing else beyond how facts are related to, and conditioned by, each other. The aspiration toward such objective knowledge belongs to the highest of which man is capable, and you will certainly not suspect me of wishing to belittle the achievements and the heroic efforts of man in this sphere. Yet it is equally clear that knowledge of what is does not open the door directly to what should be. One can have the clearest and most complete knowledge of what is, and yet not be able to deduct from that what should be the goal of our human aspirations. Objective knowledge provides us with powerful instruments for the achievements of certain ends, but the ultimate goal itself and the longing to reach it must come from another source. And it is hardly necessary to argue for the view that our existence and our activity acquire meaning only by the setting up of such a goal and of corresponding values. The knowledge of truth as such is wonderful, but it is so little capable of acting as a guide that it cannot prove even the justification and the value of the aspiration toward that very knowledge of truth. Here we face, therefore, the limits of the purely rational conception of our existence.. . .
The highest principles for our aspirations and judgments are given to us in the Jewish-Christian religious tradition. It is a very high goal which, with our weak powers, we can reach only very inadequately, but which gives a sure foundation to our aspirations and valuations. . . .
("Science and Religion," cited in Einstein's Ideas and Opinions, pp. 41-49; from an address at Princeton Theological Seminary, 19 May 1939. It was also published in Out of My Later Years [New York: Philosophical Library, 1950].
Does there truly exist an insuperable contradiction between religion and science? Can religion be superseded by science? The answers to these questions have, for centuries, given rise to considerable dispute and, indeed, bitter fighting. Yet, in my own mind there can be no doubt that in both cases a dispassionate consideration can only lead to a negative answer.
. . . the function of setting up goals and passing statements of value transcends its domain. While it is true that science, to the extent of its grasp of causative connections, may reach important conclusions as to the compatibility and incompatibility of goals and evaluations, the independent and fundamental definitions regarding goals and values remain beyond science's reach.. . .
There are many such questions which, from a rational vantage point, cannot easily be answered or cannot be answered at all. Yet, I do not think that the so-called "relativistic" viewpoint is correct, not even when dealing with the more subtle moral decisions.. . .
The interpretation of religion, as here advanced, implies a dependence of science on the religious attitude, a relation which, in our predominantly materialistic age, is only too easily overlooked. While it is true that scientific results are entirely independent from religious or moral considerations, those individuals to whom we owe the great creative achievements of science were all of them imbued with the truly religious conviction that this universe of ours is something perfect and susceptible to the rational striving for knowledge. If this conviction had not been a strongly emotional one and if those searching for knowledge had not been inspired by Spinoza's Amor Dei Intellectualis, they would hardly have been capable of that untiring devotion which alone enables man to attain his greatest achievements.
("Religion and Science: Irreconcilable?": response to a greeting sent by the Liberal Ministers' Club of New York City. Published in The Christian Register, June, 1948. Published in Ideas and Opinions [Crown Publishers, Inc., New York, 1954])
GUEST: I have a letter that Albert Einstein wrote to my father in 1943. In 1940, my father read a “Time Magazine” article that stated that Einstein was quoted as saying that the only social institution that stood up to Nazism was the Christian Church. My father is a Presbyterian minister in a little northern Michigan town called Harbor Springs. And he quoted Einstein in a sermon, and a member of the congregation wrote my father a letter saying, "Where did you get your information?" So my father wrote “Time Magazine” and “Time Magazine” wrote him back, and I have that letter, too, but they didn't give the source, so my father wrote Einstein and he wrote back, saying, yes, he did say that the Christian Church was standing up to Hitler and Nazism.
[ . . . ]
APPRAISER: The second reason I really like this story is that your dad kept all the supporting material behind the letter that he eventually got from Einstein confirming, "Yes, I did say this about the Christian Church. It is the only social institution that could stand up to the Nazi regime." . . . If you had brought this letter in without the supporting documents, I would have looked at it, and it says, "It's true that I made a statement which corresponds approximately with the text you quoted. I made this statement during the first years of the Nazi regime-- much earlier than 1940-- and my expressions were a little more moderate." And I would say, "Well, that's a nice typed letter from Einstein, says something about Nazis," but I wouldn't really know what he was talking about if your father had not saved all the material that is appropriate to it.
("1943 Albert Einstein Letter," Antiques Roadshow [PBS], 19 May 2008; the letter was appraised at $5000)
Our time is distinguished by wonderful achievements in the fields of scientific understanding and the technical application of those insights. Who would not be cheered by this? But let us not forget that human knowledge and skills alone cannot lead humanity to a happy and dignified life. Humanity has every reason to place the proclaimers of high moral standards and values above the discoverers of objective truth. What humanity owes to personalities like Buddha, Moses, and Jesus ranks for me higher than all the achievements of the enquiring and constructive mind.
What these blessed men have given us we must guard and try to keep alive with all our strength if humanity is not to lose its dignity, the security of its existence, and its joy in living.
All religions, arts and sciences are branches of the same tree. All these aspirations are directed toward ennobling man’s life, lifting it from the sphere of mere physical existence and leading the individual towards freedom. It is no mere chance that our older universities developed from clerical schools. Both churches and universities — insofar as they live up to their true function — serve the ennoblement of the individual. They seek to fulfill this great task by spreading moral and cultural understanding, renouncing the use of brute force.
(In "Moral Decay" , also published in Out of My Later Years  )
The longing to behold this pre-established harmony is the source of the inexhaustible patience and perseverance with which Planck has devoted himself, as we see, to the most general problems of our science, refusing to let himself be diverted to more grateful and more easily attained ends. I have often heard colleagues try to attribute this attitude of his to extraordinary will-power and discipline -- wrongly, in my opinion. The state of mind which enables a man to do work of this kind is akin to that of the religious worshiper or the lover; the daily effort comes from no deliberate intention or program, but straight from the heart.
("Principles of Research": address by Albert Einstein in 1918 for the Physical Society, Berlin, on the occasion of Max Planck's sixtieth birthday)
One may say "the eternal mystery of the world is its comprehensibility."
("Physics and Reality" in Journal of the Franklin Institute [March 1936]; reprinted in Out of My Later Years  )
I fully agree with you about the significance and educational value of methodology as well as history and philosophy of science. So many people today — and even professional scientists — seem to me like someone who has seen thousands of trees but has never seen a forest. A knowledge of the historic and philosophical background gives that kind of independence from prejudices of his generation from which most scientists are suffering. This independence created by philosophical insight is — in my opinion — the mark of distinction between a mere artisan or specialist and a real seeker after truth.
(Letter to Robert A. Thorton, Physics Professor at University of Puerto Rico: 7 December 1944; EA-674, Einstein Archive, Hebrew University, Jerusalem)
What I am really interested in is knowing whether God could have created the world in a different way; in other words, whether the requirement of logical simplicity admits a margin of freedom.
(in Jammer, ibid., p. 124)
I want to know how God created this world. I'm not interested in this or that phenomenon, in the spectrum of this or that element. I want to know His thoughts, the rest are details.
(E. Salaman, "A Talk with Einstein," The Listener 54 : 370-371)
I have never imputed to Nature a purpose or a goal, or anything that could be understood as anthropomorphic. What I see in Nature is a magnificent structure that we can comprehend only very imperfectly, and that must fill a thinking person with a feeling of "humility." This is a genuinely religious feeling that has nothing to do with mysticism.
(Reply to a letter: 1954 or 1955; from Helen Dukas and Banesh Hoffmann, Albert Einstein, the Human Side [Princeton Univ. Press, 1981], p. 39)
You find it strange that I consider the comprehensibility of the world (to the extent that we are authorized to speak of such a comprehensibility) as a miracle or an eternal mystery. Well a priori one should expect a chaotic world which cannot be grasped by the mind in anyway. One could (yes one should) expect the world to be subjected to law only to the extent that we order it through our intelligence. Ordering of this kind would be like the alphabetical ordering of the words of a language. By contrast, the kind of order created by Newton's theory of gravitation, for instance, is wholly different. Even if the axioms of the theory are proposed by man, the success of such a project presupposes a high degree of ordering of the objective world, and this could not be expected a priori. That is the "miracle" which is being constantly re-enforced as our knowledge expands.
There lies the weaknesss of positivists and professional atheists who are elated because they feel that they have not only successfully rid the world of gods but "bared the miracles." Oddly enough, we must be satisfied to acknowledge the "miracle" without there being any legitimate way for us to approach it.
(Letter to Maurice Solovine; from Robert N. Goldman, Einstein's God—Albert Einstein's Quest as a Scientist and as a Jew to Replace a Forsaken God [Joyce Aronson Inc.; Northvale, New Jersey; 1997], p. 24)
The idea of a personal God is quite alien to me and seems even naive. However, I am also not a "Freethinker" in the usual sense of the word because I find that this is in the main an attitude nourished exclusively by an opposition against naive superstition. My feeling is insofar religious as I am imbued with the consciousness of the insufficiency of the human mind to understand deeply the harmony of the Universe which we try to formulate as "laws of nature." It is this consciousness and humility I miss in the Freethinker mentality. Sincerely yours, Albert Einstein.
(Letter to A. Chapple, Australia, 23 February 1954; Einstein Archive 59-405; also quoted in Otto Nathan and Heinz Norden, Einstein on Peace, [Random House Value Publishing; Avenel 1981 edition], p. 510)
Originally uploaded by Dave Armstrong on 17 February 2003. Expanded greatly on 26 August 2010.