Baptism is an act that shows others publicly your decision to follow Jesus. It is the first action of obedience that believers are commanded to do.
“Therefore, go and make disciples of all the nations, baptizing them in the name of the Father and the Son and the Holy Spirit.”
“Those who believed what Peter said were baptized and added to the church that day—about 3,000 in all.”
What It Means
Being baptized literally means to be immersed. First of all, it's how Jesus did it:
“As Jesus came up out of the water, he saw the heavens splitting apart and the Holy Spirit descending on him like a dove. ”
It also signifies dying to our sins, being buried and coming back to life anew in Christ.
“...when I tried to keep the law, it condemned me. So I died to the law—I stopped trying to meet all its requirements—so that I might live for God. My old self has been crucified with Christ. It is no longer I who live, but Christ lives in me. So I live in this earthly body by trusting in the Son of God, who loved me and gave himself for me.”
Why We Do It
Baptism is NOT a part of salvation. It is simply obeying God by following Jesus in what He did. It represents dying to our sins and raising to a new life in Christ.
“One day Jesus came from Nazareth in Galilee, and John baptized him in the Jordan River.”
“Or have you forgotten that when we were joined with Christ Jesus in baptism, we joined him in his death? For we died and were buried with Christ by baptism. And just as Christ was raised from the dead by the glorious power of the Father, now we also may live new lives.”