From what I read in the New Testament, immersion is the prescribed method of baptism. But why should this be so? Because baptism is an outward confession of a person's commitment to follow Christ.
Paul, explaining why we mustn't practice sin now that we're saved, described baptism as being symbolically burried with Christ and rising again through his sacrifice on the cross. In Romans 6: 3 to 6 (BBE), he wrote, "Or are you without the knowledge that all we who had baptism into Christ Jesus, had baptism into his death? We have been placed with him among the dead through baptism into death: so that as Christ came again from the dead by the glory of the Father, we, in the same way, might be living in new life. For, if we have been made like him in his death, we will, in the same way, be like him in his coming to life again; Being conscious that our old man was put to death on the cross with him, so that the body of sin might be put away, and we might no longer be servants to sin."
Two kinds of baptism were mentioned in the New Testament. The first was a baptism of repentence which John the Baptist preached. The second was the baptism into Christ.
In Acts 19:1 to 4 (BBE), Luke wrote, "And it came about that while Apollos was at Corinth, Paul, having gone through the higher country, came to Ephesus, where there were certain disciples: And he said to them, 'Did you get the Holy Spirit when you had faith?' And they said to him, 'No, we have had no knowledge of the Holy Spirit.' And he said, 'What sort of baptism did you have?' And they said, 'The baptism of John.' And Paul said, 'John gave a baptism which goes with a change of heart, saying to the people that they were to have faith in him who was coming after him, that is, in Jesus.'"
I suppose those who believe in sprinkling get this from verses such as Hebrews 9:19 (KJV) which reads, "For when Moses had spoken every precept to all the people according to the law, he took the blood of calves and of goats, with water, and scarlet wool, and hyssop, and sprinkled both the book, and all the people,"
But the whole point of the book of Hebrews is to show the superiority of Christ over the law, angels, and all other things. Hebrews 10:22 (KJV) explains the need to be baptized as well as separated from sin. "Let us draw near with a true heart in full assurance of faith, having our hearts sprinkled from an evil conscience, and our bodies washed with pure water."
Since we are under the new covenant, we need to abide by it and not Israel's old covenant. Jesus himself initiated this new contract when he gave his disciples bread and wine at the last supper.
This is also why believer's baptism is needed. Infants can't decide to follow Christ. Neither does christening do anything to secure an offspring's salvation.
I'll be pointing out salvation by grace alone, not by ceremonies, in my next book called You Think You're Going to Heaven? Since God set the rules, our opinions don't change a thing.
My Saturday Song post will be about a song by Bachman-Turner Overdrive and individuals who are inconsistant in their conduct.