Being born again is an act of God, specifically, it is His Spirit working in us
John 1:12-13 (born again from God)
John 6:63; 2 Cor 3:6;
John 3:3-8 - being born again = being born of the Spirit
Titus 3:4-7 is also very instructive in helping us to see how the Spirit is at work in regeneration / conversion.
4 But when the goodness and loving kindness of God our Savior appeared, 5 he saved us, not because of works done by us in righteousness, but according to his own mercy, by the washing of regeneration and renewal of the Holy Spirit, 6 whom he poured out on us richly through Jesus Christ our Savior, 7 so that being justified by his grace we might become heirs according to the hope of eternal life.
How is it that we are actually made a new creation? How is it that we actually go from death to life? The question is really, “How are we converted?” There are many places in the Bible that gives metaphors for us being converted, but here in this passage we have a clear straightforward teaching about how that happens. It happens as we are regenerated and renewed - and that regeneration and renewal happens through the work of the Holy Spirit.
This does not override the responsibility that we have to respond to God. The Bible is clear that faith and repentance must happen to be saved, and those are things that we are commanded to do. But at the same time the Bible is also clear, if God does not work in us and change our hearts, then we will not come to Him. We will stay blind, dead, unborn, imprisoned, and unable to enter into the kingdom of God.
This is why faith is spoken of as a gracious gift of God (Phil 1:29; Eph 2:8-9; Eph 6:23; 2 Pet 1:1; Acts 5:31; 11:18; 2 Tim 2:25).