Jesus said: "I tell you the truth, no one can see the kingdom of God unless he is born again."¹

When we are born into this world, we are born into sin and death.  When we are "born again" we are reborn spiritually into God's family.  Having turned to God in repentance through faith in Christ Jesus as Lord and Savior, we are "born again" into righteousness and eternal life.²

Christian baptism is a symbol of this.  As we stand in the water, we are testifying that we were in Christ Jesus when sin was judged on the cross of Calvary by God.  As we are lowered under the water, we are testifying that we died with Christ Jesus, and were buried with Him.  When we come up out of the water, we are testifying that we have arisen to a new life in Christ Jesus (we are born again.)³  As the Bible says: "Therefore, if anyone is in Christ, he is a new creation; the old (life) has gone, the new (life) has come!"⁴

Bible References:

¹ (John 3:3   NIV)

² (Romans 5:12-21)

³ (Romans 6:3-4)

⁴ (2 Corinthians 5:17   NIV, words in parenthesis are mine)