Being "born again" refers to a spiritual rebirth, not a physical one. It involves being born of both water (baptism) and spirit (the Holy Spirit) according to Jesus' words in John 3:5. This new birth is necessary to enter God's kingdom, as Jesus stated in John 3:3 that unless one is born again, they cannot see the kingdom of God. The new birth transforms believers into a new creation through faith and baptism, allowing them to walk in newness of life with God forever.