In John 3:1-18, Jesus explained to Nicodemus, a Jewish leader (v.1, 10), that man needs to be born two times in order to be saved (v. 3-8). In explaining this to him, Jesus contrasts the physical birth from a spiritual birth. He said, "Except a man be born of water and of the Spirit, he cannot enter into the kingdom of God. That which is born of the flesh is flesh; and that which is born of the Spirit is spirit" (v. 5-6). Notice that being born of water refers to a physical birth ("of the flesh, is flesh"); while being born of the Spirit refers to a spiritual birth. What was true for Nicodemus, is true for all who would be saved.
Some might wonder how I went from being "born again," to being saved. It is easy; by the context of the passage. Jesus is still speaking to Nicodemus when He says:
"And as Moses lifted up the serpent in the wilderness, even so must the Son of man be lifted up: that whosoever believeth in Him should not perish, but have eternal life. For God so loved the world, that He gave His only begotten Son, that whosoever believeth in Him should not perish, but have everlasting life. For God sent not His Son into the world to condemn the world; but that the world through Him might be saved. He that believeth on Him is not condemned: but he that believeth not is condemned already, because he hath not believed in the name of the only begotten Son of God" (v. 14-18).
Jesus, both the Son of God, and the Son of man, "was lifted up" (crucified) to provide the only way for man to be saved (Jn. 14:6). When the Holy Spirit convinces us that we are sinners in need of a Savior (Jn. 16:9), that Jesus was resurrected and ascended into heaven (Jn. 16:10; Acts 1:9), and that we will all face the certain judgment of God in our future (Jn. 16:11), we are born again. In other words, we are made spiritually alive as a result of believing the Gospel (Eph. 2:1, 5; Col. 2:13; 1 Cor. 15:3-4)!
Like the wheat and tares, the Church is made up of born again believers and the lost!
Only two people know the truth about you: Jesus Christ and you!