The following explanation is from the sermon "Why Shouldn't I Be Baptized?" given by Alistair Begg. You may listen to the sermon in its entirety by clicking here>
Why do we baptize?
1) The answer is that we baptize because Jesus said we should. Very straightforward. Jesus commanded His apostles to go out into the world and to preach the gospel, to make disciples of men and women, baptizing them in the name of the Father and of the Son and of the Holy Spirit. In other words, Jesus commanded His church to do the baptizing, and therefore there is an implicit command to all who believe for themselves then to be baptized. Jesus Himself not only commanded this, but He enforced it in His own baptism. When John the Baptist tried to deter Him, He said, no, it was right for Him to be baptized. It was the right thing to do before God. In the language of the Bible, He said, that it is fitting to fulfill all righteousness; to fulfill the plan and purpose of God. So we baptize because it is a command of Jesus; therefore it is not an option. It is actually an obligation. If Jesus Christ is the Son of God, then we must do what He says. If Jesus Christ is my Savior, then I will want to do what He says.
2) We secondly should be baptized because it is the pattern of the New Testament Church to do so. There should be no surprise in that. In fact in the reading here from Acts, chapter 8, the pattern is set for us and it is reinforced if you simply read through the Acts of the Apostles. Mainly that the people heard the Good News being proclaimed. By God’s grace they believed the Good News that was proclaimed. And having believed the Good News as it was proclaimed, they then professed their belief in that Good News by being baptized.
