Jesus answered him, "Most assuredly, I tell you, unless one is born anew,{The word translated "anew" here and in John 3:7 (anothen) also means "again" and "from above".} he can't see the Kingdom of God."
All sin exposes men to misery here and hereafter. To escape from sin, to be happy in the world to come, it is necessary that man should be changed in his principles, his feelings, and his manner of life. This change, or the beginning of this new life, is called the “new birth,” or “regeneration.” It is so called because in many respects it has a striking analogy to the natural birth. It is the beginning of spiritual life. It introduces us to the light of the gospel. It is the moment when we really begin to live to any purpose. It is the moment when God reveals himself to us as our reconciled Father, and we are adopted into his family as his sons. And as every man is a sinner, it is necessary that each one should experience this change, or he cannot be happy or saved. This doctrine was not unknown to the Jews, and was particularly predicted as a doctrine that would be taught in the times of the Messiah. See Deuteronomy 10:16; Jeremiah 4:4; Jeremiah 31:33; Ezekiel 11:19; Ezekiel 36:25; Psalms 51:12. The change in the New Testament is elsewhere called the “new creation” 2 Corinthians 5:17; Galatians 6:15, and “life from the dead,” or a resurrection, Ephesians 2:1; John 5:21, John 5:24.