The old man Nicodemus was perplexed when Jesus told him he “must be born again!” He asked: how could he, being old, enter again into his mother’s womb and be born again??? Jesus explained to him in John 3:3-5 that this new birth is from above and that it is required to enter the kingdom of God. This birth was not to be a natural birth, but from above, one that involves “water and the Spirit.”
Jesus said this “new birth” ushers one into the kingdom of God on earth, referred to in other scriptures as the church of Jesus Christ, the family of God. Jesus, the Son of God, connected water with that new birth. The only time water is used in connection with the Christian religion is IN BAPTISM. The birth of water and the Spirit is essential to entering into the kingdom. Since baptism is a part of this new birth, it follows that baptism is essential to our entrance into the kingdom of God.
3,000 people on the Day of Pentecost entered the kingdom when they were immersed (baptized) “for the forgiveness of sins” (Acts 2:38-42). This helps us to see what the new birth is. Those who were guilty of the sin of crucifying the Lord, believed, repented and were immersed (baptised) so that their sins could be forgiven. When they did this, they were born into the family of God, the church. Also see Acts 8:26-40, 2 Cor 5:17, Col 3:1-17.