So also it is written, “The first man, Adam, became a living soul.” The last Adam became a life-giving spirit.1st Corinthians 15:45
The Apostle Paul wrote these words about Jesus, in the context of the Resurrection. In what way has Jesus become the “last Adam”?
The Greek word translated “last” is eschatos (ἔσχατος – G2078). It is contrasted with the word “first”, or protos (πρῶτος – G4413). The first Adam was given a spiritual authority, or headship, over his wife; and consequently over all of their natural posterity:
Gen 3: To the woman he said, “I will greatly multiply your pain in childbirth. In pain you will bear children. Your desire will be for your husband, and he will rule over you.”
By his fall into sin and depravity, Adam brought down all those over whom he had authority, into a natural state of sin, death, and depravity:
Adam and Eve sinned by believing the devil’s lie and eating the forbidden fruit. [Gen 3:1-6]Christian Confession of Faith, III.B.1
In so doing, Adam and Eve fell from their original state of innocence into a state of spiritual death and depravity. The guilt and defilement of Adam’s sin has been imputed to all whom he represented (all his natural posterity). The spiritual state of total depravity into which Adam fell has been transmitted to all whom he represented, and all whom he represented became physically subject to decay and death. [Gen 3:7-8,16-24; Gen 5:3-5; Psa 51:5; Rom 3:10-18; Rom 5:12-14,19; Rom 8:5-8; Eph 2:1-3; Eph 4:17-19]Christian Confession of Faith, III.B.2
Here are some of the verses that the Confession refers to:
Psa 51: Behold, I was born in iniquity. In sin my mother conceived me.
Rom 3: As it is written, “There is no one righteous; no, not one.  There is no one who understands. There is no one who seeks after God.  They have all turned aside. They have together become unprofitable. There is no one who does good, no, not so much as one.”
Rom 5: For as through the one man’s disobedience many were made sinners, even so through the obedience of the one, many will be made righteous.
Rom 7: because the mind of the flesh is hostile towards God; for it is not subject to God’s law, neither indeed can it be.  Those who are in the flesh can’t please God.
Eph 4: You were made alive when you were dead in transgressions and sins,  in which you once walked according to the course of this world, according to the prince of the power of the air, the spirit who now works in the children of disobedience;  among whom we also all once lived in the lust of our flesh, doing the desires of the flesh and of the mind, and were by nature children of wrath, even as the rest.
But just as Adam was made head over all of his natural posterity, so Jesus was made to be head over his bride, the Church:
1Co 11: But I would have you know that the head of every man is Christ, and the head of the woman is the man, and the head of Christ is God.
Eph 5: For the husband is the head of the wife, and Christ also is the head of the assembly, being himself the savior of the body.
And when a sinner is regenerated by the work of the Holy Spirit, that sinner is transferred from under the headship of Adam, to the headship of Christ:
Conversion is that grace in which the Holy Spirit causes the sinner to repent and believe the gospel. The regenerate person is given a knowledge and understanding of the true gospel of salvation conditioned on the work of Jesus Christ alone and the realization that he was unregenerate when he believed a false gospel of salvation conditioned on the sinner. He counts all of his former life and deeds, whether religious or irreligious, as dead works, evil deeds, and fruit unto death. Conversion is the immediate and inevitable fruit of regeneration; therefore, a person may not be regenerated without being converted. There has never existed and will never exist a regenerate person who is ignorant of the gospel. Scripture rejects the lie that an unregenerate person can be under the conviction of the Holy Spirit, since the Holy Spirit only leads people to Jesus Christ and His righteousness as the only ground of salvation. [Deu 4:34-35; Isa 45:6,20-25; Mat 13:23; Mar 16:16; Joh 6:40; Joh 8:32; Joh 16:8-11; Joh 17:3; Act 16:14-15; Rom 1:16-17; Rom 3:26; Rom 6:17,21; Rom 7:6; 1Co 2:10-12; 2Co 4:2-6; Eph 1:13; Phi 3:7-8; 2Th 2:13-14; Heb 9:14; 1Jo 5:20]Christian Confession of Faith, V.C.3
Here are some of the verses the Confession appeals to:
Isa 45: “Assemble yourselves and come. Draw near together, you who have escaped from the nations. Those have no knowledge who carry the wood of their engraved image, and pray to a god that can’t save.  Declare and present it. Yes, let them take counsel together. Who has shown this from ancient time? Who has declared it of old? Haven’t I, Yahweh? There is no other God besides me, a just God and a Savior; There is no one besides me.  “Look to me, and be saved, all the ends of the earth; for I am God, and there is no other.  I have sworn by myself, the word has gone out of my mouth in righteousness, and will not return, that to me every knee shall bow, every tongue shall take an oath.  They will say of me, ‘There is righteousness and strength only in Yahweh.’” Even to him shall men come; and all those who were incensed against him shall be disappointed.  In Yahweh shall all the seed of Israel be justified, and shall glory.
Joh 6: This is the will of the one who sent me, that everyone who sees the Son, and believes in him, should have eternal life; and I will raise him up at the last day.”
Rom 6: But thanks be to God, that, whereas you were bondservants of sin, you became obedient from the heart to that form of teaching to which you were delivered.
Rom 7: But now we have been discharged from the law, having died to that in which we were held; so that we serve in newness of the spirit, and not in oldness of the letter.
Eph 1: in whom you also, having heard the word of the truth, the Good News of your salvation—in whom, having also believed, you were sealed with the Holy Spirit of promise,
Heb 9: how much more will the blood of Christ, who through the eternal Spirit offered himself without defect to God, cleanse your conscience from dead works to serve the living God?
Conversion is every bit as much a gift of the Holy Spirit as regeneration, and it is always given upon regeneration. It is an essential fruit of the gift of regeneration.
One great consequence of the gift of conversion is that a believer is assured of his own salvation:
God gives every believer assurance of salvation. The believer’s assurance does not lie in his obedience to the law, his continued repentance, or anything else but in the sure and certain promise of God through the work of Jesus Christ alone received by faith. [2Sa 23:5; Psa 5:11; Psa 9:10; Psa 32:10; Psa 34:22; Psa 62:1-2,5-7; Psa 64:10; Psa 125:1; Psa 130:7-8; Psa 147:11; Isa 26:3; Isa 32:17; Jer 17:7-8; Nah 1:7; Rom 5:1; Rom 8:15-16,33-39; Rom 9:33; 2Co 1:18-22; Eph 3:12; Phi 1:6; Col 2:2; 1Th 1:5; 2Ti 1:12; Heb 6:11,16-19; Heb 10:22; Heb 11:1; Rev 5:9]Christian Confession of Faith, V.C.6
2Sa 23: Most certainly my house is not so with God, yet he has made with me an everlasting covenant, ordered in all things, and sure, for it is all my salvation, and all my desire, although he doesn’t make it grow.
Psa 34: Yahweh redeems the soul of his servants. None of those who take refuge in him shall be condemned.
Jer 17: Blessed is the man who trusts in Yahweh, and whose trust Yahweh is.  For he shall be as a tree planted by the waters, who spreads out its roots by the river, and shall not fear when heat comes, but its leaf shall be green; and shall not be careful in the year of drought, neither shall cease from yielding fruit.
Rom 8: Who could bring a charge against God’s chosen ones? It is God who justifies.  Who is he who condemns? It is Christ who died, yes rather, who was raised from the dead, who is at the right hand of God, who also makes intercession for us.  Who shall separate us from the love of Christ? Could oppression, or anguish, or persecution, or famine, or nakedness, or peril, or sword?  Even as it is written, “For your sake we are killed all day long. We were accounted as sheep for the slaughter.”  No, in all these things, we are more than conquerors through him who loved us.  For I am persuaded, that neither death, nor life, nor angels, nor principalities, nor things present, nor things to come, nor powers,  nor height, nor depth, nor any other created thing, will be able to separate us from the love of God, which is in Christ Jesus our Lord.
1Ti 1: For this cause I also suffer these things. Yet I am not ashamed, for I know him whom I have believed, and I am persuaded that he is able to guard that which I have committed to him against that day.
Heb 6: This hope we have as an anchor of the soul, a hope both sure and steadfast and entering into that which is within the veil;
Heb 11: Now faith is assurance of things hoped for, proof of things not seen.
Just as conversion is an essential fruit of regeneration, so assurance is an essential fruit of conversion.
Jesus is the last Adam, in the sense that he is the federal Head over all of his people, as Adam was over all of his natural descendants. Those who believe the Gospel have been separated from the house of Adam, to the house of Christ (Psa 45:10, Mat 10:37, Eph 5:23), by a great work of God, the Holy Spirit (Rom 8:2-11). They are given the gift of regeneration, and the knowledge that they are saved, and assured of eternal salvation. In this way, “The last Adam became a life-giving spirit”. Halellujah!
10 O daughter, take good heed,
incline, and give good ear;
Thou must forget thy kindred all,
and father’s house most dear.
11 Thy beauty to the King
shall then delightful be:
And do thou humbly worship him,
because thy Lord is he.
(Psalm 45, Second Version, The Psalms of David in Metre)
III. Anthropology – The Doctrine of Man