Regeneration is a sovereign work of God (Jn. 1:12-13; 3:3-8; Jas. 1:18; 1 Pet. 1:3) a radical work or total transformation (Ezek. 36:26-27; 1 Jn. 3:9) not just an addition...The SOURCE of regeneration is Christ (1 Pet 1:3; Eph 1:3, 2:4, 4:24; 2 Cor 5:17) The AGENT of regeneration is the Holy Spirit (Jn. 3:3-8; Titus 3:5) The INSTRUMENT of regeneration is the Word of God (Jas. 1:18; 1 Pet. 1:23, 25) which precedes and causes faith (Jn 6:63-65, 1 jn 5:1, Eph. 2:5; Col. 2:13)
"God effects a change which is radical and all-pervasive, a change which cannot be explained in terms of any combination, permutation or accumulation of human resources, a change which is nothing less than a new creation by Him who calls the things that be not as though they were, who spoke and it was done, whocommanded and it stood fast. This, in a word, is regeneration." - John Murray
Regeneration is the communication of the new heart to sinners by the operation of the Holy Spirit through the Word...a Christ-generated act of instantaneously communicating spiritual life to a man convicted of sin.
Regeneration is expressly denied to be of the will of the flesh, or of the will of man (John 1:13), and is ascribed to God himself. Not all men have faith in Christ; and those who do have it, have it not of themselves; it is the gift of God, worked out through the Redemption which is in Christ through the mighty operation of his Spirit, which is the fruit and effect of His invincible grace. This is because the natural man is wholly captive under the power and dominion of sin, and a slave unto it, and has neither a power nor will to believe the gospel of Jesus Christ apart from the regenerating work of the Holy Spirit.
Synergists teach that 'salvation depends on human will', but the Bible teaches that 'it depends not on human will or exertion, but on God, who has mercy." (Rom 9:16)
"And I will put my Spirit within you, and you shall live...Then you shall know that I am the LORD; I have spoken, and I will do it, declares the LORD." - Ezekiel 37:14
But because of his great love for us, God, who is rich in mercy, made us alive [quickened us] with Christ even when we were dead in transgressions – it is by grace you have been saved.
“It is the Spirit who gives life; the flesh is of no avail. The words that I have spoken to you are spirit and life. But there are some of you who do not believe.” (For Jesus knew from the beginning who those were who did not believe, and who it was who would betray him.) And he said, “This is why I told you that no one can come to me [i.e. believe in me] unless it is granted him by the Father.”
You have been born anew, not of perishable seed but but of imperishable, through the living and abiding word of God..."
1 Peter 1:23-25
Everyone who believes that Jesus is the Christ has been born of God.
1 John 5:1
Faith in the living God and his Son Jesus Christ is always the result of the new birth, and can never exist except in the regenerate. Whoever has faith is a saved man.
Charles Spurgeon from the sermon “Faith and Regeneration”
If salvation is the implantation of a new, infinite life in the soul, it must be a work of God. Self-caused effects can never rise above the character or qualities of their cause. "Flesh gives birth to flesh but the Spirit gives birth to Spirit," Jesus told Nicodemus. This saving grace cannot be caused by the creature, it can only come from God.
John Hannah from To God be the Glory (pg. 34-5)
The inward offer is a kind of spiritual enlightenment, whereby the promises are presented to the hearts of men, as it were, by an inward word.