Monergism

monergism
“[T]he doctrine that the Holy Spirit is the only efficient agent in regeneration—that the human will possesses no inclination to holiness until regenerated, and therefore cannot coöperate in regeneration.”1

From scripture:
And you were dead in the trespasses and sins 2 in which you once walked, following the course of this world, following the prince of the power of the air, the spirit that is now at work in the sons of disobedience— 3 among whom we all once lived in the passions of our flesh, carrying out the desires of the body and the mind, and were by nature children of wrath, like the rest of mankind. 4 But God, being rich in mercy, because of the great love with which he loved us, 5 even when we were dead in our trespasses, made us alive together with Christ—by grace you have been saved— 6 and raised us up with him and seated us with him in the heavenly places in Christ Jesus, 7 so that in the coming ages he might show the immeasurable riches of his grace in kindness toward us in Christ Jesus. 8 For by grace you have been saved through faith. And this is not your own doing; it is the gift of God, 9 not a result of works, so that no one may boast. 10 For we are his workmanship, created in Christ Jesus for good works, which God prepared beforehand, that we should walk in them. (Ephesians 2:1-10 ESV)
From The Canons of Dordt, The Third and Fourth Main Points of Doctrine:
Article 10: Conversion as the Work of God

The fact that others who are called through the ministry of the gospel do come and are brought to conversion must not be credited to man, as though one distinguishes himself by free choice from others who are furnished with equal or sufficient grace for faith and conversion (as the proud heresy of Pelagius maintains). No, it must be credited to God: just as from eternity he chose his own in Christ, so within time he effectively calls them, grants them faith and repentance, and, having rescued them from the dominion of darkness, brings them into the kingdom of his Son, in order that they may declare the wonderful deeds of him who called them out of darkness into this marvelous light, and may boast not in themselves, but in the Lord, as apostolic words frequently testify in Scripture.

Article 11: The Holy Spirit’s Work in Conversion

Moreover, when God carries out this good pleasure in his chosen ones, or works true conversion in them, he not only sees to it that the gospel is proclaimed to them outwardly, and enlightens their minds powerfully by the Holy Spirit so that they may rightly understand and discern the things of the Spirit of God, but, by the effective operation of the same regenerating Spirit, he also penetrates into the inmost being of man, opens the closed heart, softens the hard heart, and circumcises the heart that is uncircumcised. He infuses new qualities into the will, making the dead will alive, the evil one good, the unwilling one willing, and the stubborn one compliant; he activates and strengthens the will so that, like a good tree, it may be enabled to produce the fruits of good deeds.

Article 12: Regeneration a Supernatural Work

And this is the regeneration, the new creation, the raising from the dead, and the making alive so clearly proclaimed in the Scriptures, which God works in us without our help. But this certainly does not happen only by outward teaching, by moral persuasion, or by such a way of working that, after God has done his work, it remains in man’s power whether or not to be reborn or converted. Rather, it is an entirely supernatural work, one that is at the same time most powerful and most pleasing, a marvelous, hidden, and inexpressible work, which is not lesser than or inferior in power to that of creation or of raising the dead, as Scripture (inspired by the author of this work) teaches. As a result, all those in whose hearts God works in this marvelous way are certainly, unfailingly, and effectively reborn and do actually believe. And then the will, now renewed, is not only activated and motivated by God but in being activated by God is also itself active. For this reason, man himself, by that grace which he has received, is also rightly said to believe and to repent.

From Concise Theology by J. I. Packer:
Regeneration is monergistic: that is, entirely the work of God the Holy Spirit. It raises the elect among the spiritually dead to new life in Christ (Eph. 2:1-10). Regeneration is a transition from spiritual death to spiritual life, and conscious, intentional, active faith in Christ is its immediate fruit, not its immediate cause.