It is part of the gospel taught and practiced by the first Christians
In every account in the books of acts, baptism was involved in becoming a Christ follower. Baptism is not what saves one. It is just part of the plan of salvation. The person being baptized must not have their faith in their own abilities, ability of the one baptizing them, the water itself, but in the promise of Jesus' blood washing our sins away.
It is an opportunity to imitate Christ
Baptism was so important to Christians in the early church because it was important to Jesus. In Matthew, Chapter 3, Jesus ushered in His ministry on earth by being baptized.
It is an opportunity to identify with Christ
Do you know that all of us who were baptized into Christ Jesus were baptized into his death? We were therefore buried with him through baptism, into death, in order that, just as Christ was raised from the dead through the glory of the Father, we too may live a new life. ROMANS 6:3-4 (NIV)
How Should I Be Baptized?
In today's world, Christians come from a wide variety of backgrounds. You may be a Christian who grew up in a church that practices sprinkling or pouring as its form of baptism. What are you to think? If you were sprinkled, did your baptism not count? Arguments and hurt feelings sometimes erupt between Christians over such questions!
The important thing to remember if you come from such a background is that a rich, spiritual heritage is a gift from God!! Your decision to become immersed is not admission that you or your family were wrong in the way you chose to follow Christ. When you were sprinkled as a child, it was your parents' prayer that you become an adult who would serve the Lord. Your conscious decision to become an immersed belliever is God's way of answering those prayers. If you already consider yourself a devoted follower of Christ, becoming immersed will serve as a means of establishing common ground for fellowship with other believers in your new church, or, if you like, as a powerful tool for spiritual re-dedication.
Churches that practice immersion do so because it is the method of baptism that is recorded in the New Testament. The word "baptism" finds its roots from the Greek work baptismos. Literally translated, this word means "a dipping in water" (Liddell & Scott) or "immersion" (Smith's Dictionary). To become immersed is to be baptized the way Jesus and all the believers in the first century Church were. If Jesus had wanted to say pour, he would have used the word "ekcheo". If he wanted to say sprinkle, he would have said "rantizo".