When you are born again from God our heavenly Father, you are not born again physically into another mortal-natural body. No, a new body in which your soul learns to dwell is born within you: what is brought into being within you is your new, immortal-spiritual body that lasts forever. It is "the inner man of the heart" and your soul's only vehicle of escape from the natural, biological body of death. And until your outer man, your mortal-natural body, is put off at biological death, (prefigured by circumcision - the cutting & casting off of the unprofitable flesh), both the body of flesh and that of the Spirit call for your soul's attention. This is the struggle Paul writes about in Galatians:
Galatians 5:16-26 and Galatians 6:1-2
I say then: Walk in the Spirit, and you shall not fulfill the lust of the flesh. 17 For the flesh lusts against the Spirit, and the Spirit against the flesh; and these are contrary to one another, so that you do not do the things that you wish. 18 But if you are led by the Spirit, you are not under the law.
19 Now the works of the flesh are evident, which are: adultery, fornication, uncleanness, lewdness, 20 idolatry, sorcery, hatred, contentions, jealousies, outbursts of wrath, selfish ambitions, dissensions, heresies, 21 envy, murders, drunkenness, revelries, and the like; of which I tell you beforehand, just as I also told you in time past, that those who practice such things will not inherit the kingdom of God.
22 But the fruit of the Spirit is love, joy, peace, longsuffering, kindness, goodness, faithfulness, 23 gentleness, self-control. Against such there is no law. 24 And those who are Christ's have crucified the flesh with its passions and desires. 25 If we live in the Spirit, let us also walk in the Spirit. 26 Let us not become conceited, provoking one another, envying one another.
6:1 Brethren, if a man is overtaken in any trespass, you who are spiritual restore such a one in a spirit of gentleness, considering yourself lest you also be tempted. 2 Bear one another's burdens, and so fulfill the Law of Christ.
3:1 There was a man of the Pharisees named Nicodemus, a ruler of the Jews. 2 This man came to Jesus by night and said to Him, "Rabbi, we know that You are a teacher come from God; for no one can do these signs that You do unless God is with him."
3 Jesus answered and said to him, "Most assuredly, I say to you, unless one is born again, he cannot see the kingdom of God."
4 Nicodemus said to Him, "How can a man be born when he is old? Can he enter a second time into his mother's womb and be born?"
5 Jesus answered, "Most assuredly, I say to you, unless one is born of water and the Spirit, he cannot enter the kingdom of God. 6 That which is born of the flesh is flesh, and that which is born of the Spirit is spirit. 7 Do not marvel that I said to you, 'You must be born again.' 8 The wind blows where it wishes, and you hear the sound of it, but cannot tell where it comes from and where it goes. So is everyone who is born of the Spirit."
9 Nicodemus answered and said to Him,"How can these things be?"
10 Jesus answered and said to him, "Are you the teacher of Israel, and do not know these things? 11 Most assuredly, I say to you, We speak what We know and testify what We have seen, and you do not receive Our witness. 12 If I have told you earthly things and you do not believe, how will you believe if I tell you heavenly things? 13 No one has ascended to heaven but He who came down from heaven, that is, the Son of Man who is in heaven. 14 And as Moses lifted up the serpent in the wilderness, even so must the Son of Man be lifted up, 15 that whoever believes in Him should not perish but have eternal life. 16 For God so loved the world that He gave His only begotten Son, that whoever believes in Him should not perish but have everlasting life. 17 For God did not send His Son into the world to condemn the world, but that the world through Him might be saved.
18 "He who believes in Him is not condemned; but he who does not believe is condemned already, because he has not believed in the name of the only begotten Son of God. 19 And this is the condemnation, that the light has come into the world, and men loved darkness rather than light, because their deeds were evil. 20 For everyone practicing evil hates the light and does not come to the light, lest his deeds should be exposed. 21 But he who does the truth comes to the light, that his deeds may be clearly seen, that they have been done in God."
The Spirit gives life; the flesh counts for nothing. The words I have spoken to you are spirit and they are life.
1 Corinthians 15:50-57
Now this I say, brethren, that flesh and blood cannot inherit the kingdom of God; nor does corruption inherit incorruption. 51 Behold, I tell you a mystery: We shall not all sleep, but we shall all be changed — 52 in a moment, in the twinkling of an eye, at the last trumpet. For the trumpet will sound, and the dead will be raised incorruptible, and we shall be changed. 53 For this corruptible must put on incorruption, and this mortal must put on immortality. 54 So when this corruptible has put on incorruption, and this mortal has put on immortality, then shall be brought to pass the saying that is written: "Death is swallowed up in victory."
55 "O Death, where is your sting?
O Hades, where is your victory?"
56 The sting of death is sin, and the strength of sin is the law. 57 But thanks be to God, who gives us the victory through our Lord Jesus Christ.