St. Paul was vehemently opposed to the Protestant faith alone (sola fide) doctrine and to monergism
Romans 13:11-14 Besides this you know what hour it is, how it is full time now for you to wake from sleep. For salvation is nearer to us now than when we first believed;  the night is far gone, the day is at hand. Let us then cast off the works of darkness and put on the armor of light;  let us conduct ourselves becomingly as in the day, not in reveling and drunkenness, not in debauchery and licentiousness, not in quarreling and jealousy.  But put on the Lord Jesus Christ, and make no provision for the flesh, to gratify its desires.
1 Corinthians 9:22-27 To the weak I became weak, that I might win the weak. I have become all things to all men, that I might by all means save some.  I do it all for the sake of the gospel, that I may share in its blessings.  Do you not know that in a race all the runners compete, but only one receives the prize? So run that you may obtain it.  Every athlete exercises self-control in all things. They do it to receive a perishable wreath, but we an imperishable.  Well, I do not run aimlessly, I do not box as one beating the air;  but I pommel my body and subdue it, lest after preaching to others I myself should be disqualified.
Philippians 2:12-13 Therefore, my beloved, as you have always obeyed, so now, not only as in my presence but much more in my absence, work out your own salvation with fear and trembling;  for God is at work in you, both to will and to work for his good pleasure.
Philippians 3:7-16 But whatever gain I had, I counted as loss for the sake of Christ.  Indeed I count everything as loss because of the surpassing worth of knowing Christ Jesus my Lord. For his sake I have suffered the loss of all things, and count them as refuse, in order that I may gain Christ  and be found in him, not having a righteousness of my own, based on law, but that which is through faith in Christ, the righteousness from God that depends on faith;  that I may know him and the power of his resurrection, and may share his sufferings, becoming like him in his death,  that if possible I may attain the resurrection from the dead.  Not that I have already obtained this or am already perfect; but I press on to make it my own, because Christ Jesus has made me his own.  Brethren, I do not consider that I have made it my own; but one thing I do, forgetting what lies behind and straining forward to what lies ahead,  I press on toward the goal for the prize of the upward call of God in Christ Jesus.  Let those of us who are mature be thus minded; and if in anything you are otherwise minded, God will reveal that also to you.  Only let us hold true to what we have attained.
2 Thessalonians 2:13 . . . God chose you from the beginning to be saved, through sanctification by the Spirit and belief in the truth.
1 Timothy 2:15 Yet woman will be saved through bearing children, if she continues in faith and love and holiness, with modesty.
1 Timothy 4:16 Take heed to yourself and to your teaching; hold to that, for by so doing you will save both yourself and your hearers.
2 Timothy 3:15 . . . the sacred writings which are able to instruct you for salvation through faith in Christ Jesus. [we do the work of reading Scripture and this in turn can save us, so we helped save ourselves by reading it]
Hebrews 6:9-11 Though we speak thus, yet in your case, beloved, we feel sure of better things that belong to salvation.  For God is not so unjust as to overlook your work and the love which you showed for his sake in serving the saints, as you still do.  And we desire each one of you to show the same earnestness in realizing the full assurance of hope until the end,
1 Peter 2:2 Like newborn babes, long for the pure spiritual milk, that by it you may grow up to salvation;
2 Peter 1:10 Therefore, brethren, be the more zealous to confirm your call and election, for if you do this you will never fall;
Final Judgment in Scripture is Always Associated With Works And Never With Faith Alone (50 Passages) (+ Discussion)
"Work Out Your Own Salvation With Fear and Trembling" (Philippians 2:12): Does It Harmonize With Protestant Soteriology? (Dave Armstrong vs. Ken Temple) (+ Discussion)
The Interpretation and Exegesis of Romans 2-4 (Justification and Works of the Law) (Includes Very Extensive Patristic Commentary and Definitional Citations from three Protestant Bible Dictionaries)
Biblical Evidence For Merit and "Quantifiable" Grace (+ Discussion)
Dialogue: "Doing Something" for Salvation (Dave Armstrong vs. Craig Kott)
Catholic-Baptist Dialogue on "Being Good Enough" to Go to Heaven, etc. (Dave Armstrong vs. "Grubb")
Is Catholic Soteriology Pelagian? (Reginald de Piperno) (+ Discussion)
1 Corinthians 3:9 and Man's Cooperation With God
Human, Pauline, and Marian Distribution of Divine Graces: Not an "Unbiblical" Notion After All?
A Primer on Semi-Pelagianism and Arminianism
Grace Alone (Sola Gratia): Perfectly Acceptable Biblical and Catholic Teaching (Rightly Understood)
Merit: Clarification of the Catholic Doctrine (Condign and Congruous Merit, Total Depravity, Prevenient Grace, Etc.) (+ Discussion)
Soteriology and Creation (Man's Cooperation, Pelagianism, Nature and Grace) (Dave Armstrong vs. Peter J. Leithart)Second Council of Orange (529) and Catholic Sola Gratia vs. Calvinist Total Depravity, Etc.: Crucial Distinctions Noted (+ Discussion)
The Calvinist Doctrine of Total Depravity and Romans 3:10-11 ("None is Righteous . . . No One Seeks For God"): Reply to James White (+ Discussion)Do Catholics Believe in Predestination?
Catholic Predestination (Ludwig Ott)