Very simply, baptism is an outward testimony of the inward change in a believer’s life. Christian baptism is an act of obedience to the Lord after salvation; although baptism is closely associated with salvation, it is not a requirement to be saved. The Bible shows in many places that the order of events is 1) a person believes in the Lord Jesus and 2) he is baptized. This sequence is seen in Acts 2:41, “Those who accepted [Peter’s] message were baptized” (see also Acts 16:14–15).
A new believer in Jesus Christ should desire to be baptized as soon as possible. In Acts 8 Philip speaks “the good news about Jesus” to the Ethiopian eunuch, and, “as they traveled along the road, they came to some water and the eunuch said, ‘Look, here is water. What can stand in the way of my being baptized?’” (verses 35–36). Right away, they stopped the chariot, and Philip baptized the man.
Baptism illustrates a believer’s identification with Christ’s death, burial, and resurrection. Everywhere the gospel is preached and people are drawn to faith in Christ, they are to be baptized.
Grace Bible Fellowship’s position on baptism says:
About Baptism by Immersion – We believe that scriptural baptism must be: (1) by being completely immersed under the water and (2) after salvation. Baptism has no saving power but is the first act of obedience symbolizing (1) the believer’s faith in the death, burial, and resurrection of Jesus, (2) the believer’s death to sin and resurrection to walk anew in Christ, and (3) the Christian’s belief that he will die, be buried, and that Jesus will resurrect him from the dead. Acts 8:26-39; Romans 6:4, 5; Colossians 2:12