Baptism is an act of obedience that Jesus himself did as an example for us to follow. It is an important part of one's decision to become a follower of Christ. It is a pledge of allegiance, a total physical commitment. Baptism says "all of me belongs to Him"
We baptize by immersion because this is the way it was practiced by the apostles and the early church. The original text for the New Testament was written in Greek. Upon studying the original text, we see that the definition for the Greek word used for "baptism" is "to immerse or plunge under water".
Matthew 28:19-20; Acts 2:38-41; 8:35-38; 16:30-34; Romans 6:3-5; Galatians 3:26-27