In Believer's Immersion baptism, the person being baptized is publicly professing his or her own decision to accept Christ as their Savior. It is considered a step of obedience following one’s declaration of faith in Jesus Christ.
"Repent and be baptized, every one of you, in the name of Jesus Christ for the forgiveness of your sins. And you will receive the gift of the Holy Spirit.”
Throughout the gospels and the book of Acts there are numerous examples of people believing and being baptized. Typically, believer's baptism takes place by immersion, following the example of Christ’s immersion in the Jordan River.