“That which is born of the flesh is flesh, and that which is born of the Spirit is spirit. Do not marvel that I said to you, ‘You must be born again.’” – John 3:6–7
Birth is the beginning of life. Our first birth, through the flesh, makes us part of an earthly family. But Jesus is clear: “that which is born of the flesh is flesh.” The flesh here means our fallen human nature; corrupt, sinful, and weak. That we inherited through Adam’s sin, “sin entered the world, and death through sin, and thus death spread to all men” (Romans 5:12). By nature, we are born separated from God, with desires and inclinations that cannot please Him. “Those who are in the flesh cannot please God” (Romans 8:8).
This is where we understand Jesus is teaching Nicodemus that no amount of human effort, law-keeping, or religion can make someone fit for God’s Kingdom. Human birth produces human life, but not spiritual life. That is why Jesus said, “Do not marvel that I said to you, ‘You must be born again.’”
By our first birth, we were corrupt, shaped in sin. David said, “Behold, I was brought forth in iniquity, and in sin my mother conceived me” (Psalm 51:5). Because of this, a new birth is necessary. We must be made new creatures. “If anyone is in Christ, he is a new creation; old things have passed away; behold, all things have become new” (2 Corinthians 5:17).
This new birth is not something we can achieve in our own strength. It is a work that only the Spirit of God can accomplish, changing us from the inside out. “As many as received Him, to them He gave the right to become children of God, to those who believe in His name: who were born, not of blood, nor of the will of the flesh, nor of the will of man, but of God” (John 1:12–13). It is God who put His Spirit within us to gave us a new heart that belongs to Him.
By the Spirit’s work, we receive a new nature, new principles, new desires, and new aims. The Holy Spirit gives us the power to put off the old life of sin and walk in righteousness. But those who are born of the Spirit bear fruit that cannot come from the flesh: “lBut the fruit of the Spirit is love, joy, peace, longsuffering, kindness, goodness, faithfulness, gentleness, self-control. Against such there is no law. And those who are Christ’s have crucified the flesh with its passions and desires. (Galatians 5:22–24)
And this explains why the world often cannot understand believers. “The natural man does not receive the things of the Spirit of God, for they are foolishness to him; nor can he know them, because they are spiritually discerned” (1 Corinthians 2:14). Those still in the flesh cannot comprehend the life of the Spirit, because spiritual rebirth is something only God can give.
The Spirit not only makes us new but also seals us. “In Him you also trusted, after you heard the word of truth, the gospel of your salvation; in whom also, having believed, you were sealed with the Holy Spirit of promise, who is the guarantee of our inheritance” (Ephesians 1:13–14). The Spirit assures us we belong to God, strengthens us in our weakness (Romans 8:26), transforms us into the image of Christ (2 Corinthians 3:18), and guides us into all truth (John 16:13).
So Jesus’ words to Nicodemus remain urgent for us today!! “That which is born of the flesh is flesh, and that which is born of the Spirit is spirit… You must be born again.” The flesh we have cannot inherit God’s Kingdom. Only through the baptism of the Holy Spirit’s bring new birth that we become children of God and enter into His Kingdom.
