As it is written, "The spirit and the flesh are at war, so you cannot do as you please."
Before a person is Born of God, they are completely "In the flesh". That is to say, their spirit is truly "godless" and it includes everyone since the first trangression of mankind. They are either alone, or possessed by devils, living within the darkness of their own soul, and they are COMPLETELY bound to their own carnal "man" (that is the "flesh") to obey it's every desire, aka the desires of the flesh. They are literally "in the flesh". Their spirit and their sinful flesh are united, their soul is enchained to the desires of the body, which is in turn, led and dominated by the whole "world", which is completely under the power of Satan. So before you receive the Holy Spirit, the order of Authority for the condemned goes like this... Satan>World>Flesh>You.
When a person is "Born Again", the Spirit of God, aka the Spirit of Christ, is deposited thru Christ into the soul of the person and thereby God joins Himself with "YOU" within your soul, joining His Spirit with yours, and gently becoming the Lord of your heart/soul, and you become unified or "one" with God in Spirit. The Spirit of God, having been placed in believers, making them "Born Again", grows within them the desire and ability to Obey the Will of God. So AFTER you receive the Spirit of God, the order of authority for the Redeemed/saved/delivered goes like this Father>Son>Spirit>You>Your Body This is the ORIGINAL CONDITION God created Man to be in. And it results in PEACE WITH GOD AND EVERYTHING ELSE (except those under Satan's power. See above)
This is the 'reconciliation' Jesus Christ made possible when He BECAME sin for us on the Cross, bearing our iniquity in His OWN body, and having His own Righteous Blood poured out for our sins. Jesus IS the only True and Spotless Lamb of God who takes away our sins! (Thank you Jesus!). His Death was for our Sanctification (being picked out and cleaned) and His resurrection was for our "justification" (making right the wrong we had done against God). Now anyone born of God cannot continue to sin because (as it is written) "the seed of God dwells in him, and he cannot continue to sin". The Spirit of God fills the believer in Jesus Christ with the very Spirit of the Power of God that resurrected Jesus from the grave, and thereby allows the believer to follow in the Way of God and have dominion (power and authority) OVER their flesh, instead of being DOMINATED by their flesh. As Paul said (and this is true of all, even those "Born Again").... "There is NOTHING GOOD in me, that is in my flesh (specifically)". The Holy Spirit is the only Good in ANYONE except God. EVERYTHING about God is truly Good.
Whoever is "unborn" (not yet born of God) is COMPLETELY dominated by their flesh, bound to do it's desires, which (since sin entered the world) will always tempt, leading them to sin, which will lead to death, Hell, and the Lake of Fire, because it (the "flesh") is by nature, our sinful nature (ever since the entry of sin into the world that occurred when man sinned). This is why Jesus earnestly said "You MUST be Born Again." and again He said "Unless a man is Born Again, he CANNOT see the Kingdom of Heaven".
Therefore, the "second birth" is NECESSARY to overcome sin in your flesh, sin in the world, and the power of the tempter, our Enemy Satan, who desires all men to be destroyed. Only being "Born Again" aka "Born from Above", or receiving the "Second Birth", aka "Receiving the Spirit", etc..... will allow you to overcome the Devil, this corrupted world, and the very sin in your own flesh. This is because God's own Holy Spirit is given to all who believe in Jesus and ask the Father for the Spirit of Holiness. Jesus did the work. The Holy Spirit finishes it in us. And God receives all the Glory and all my praise. Forever. AMEN!
You MUST be Born Again!