Water baptism is symbolic to dying to the flesh and being resurrected in the Spirit. There are two baptisms. Water Baptism and the Baptism of the Holy Spirit. Jesus said you must be Born Again in order to enter the Kingdom Of God. Born of the Spirit.
If you are baptized in the church, it means you were cleansed with water, by a priest who prayed for you to receive the holy spirit, and to be what is called reborn, it is said that one must actually be emerged into the water completely and taken back up from the priest, though babies are often sprinkled with water.
Baptism is a public declaration of the dedication you have made to God in your heart by means of prayer. The Bible says that baptism is an important step to gaining salvation. (1 Peter 3:21) This doesn’t mean, though, that baptism is like an insurance policy that you buy to protect yourself in case disaster should strike. You get baptized because you love Jehovah and want to serve him forever with your whole heart.—Mark 12:29, 30.
Going down under the water is a picture of Jesus' death and burial for sin. Coming back out of the water is a picture of Jesus' resurrection from the dead. Baptism shows a believer is united with Jesus in His death and resurrection. Because Jesus died and rose to conquer sin, at salvation a believer dies to his old, sinful self and is raised to new life in Christ. Baptism is a picture of what happens to a believer at salvation.