Baptism = Purification
You have to believe, to repent, and produce a product worthy of repentment. Jesus said to Nicodemus: you have to born again (John 3). The same way Paul says (to Romans 6. 2 to 7) that baptism is the passage from death to life, and compared with the death and resurrection of Jesus (new birth).
To represent the baptism, four important steps are necessary, as Paul puts in Rm:
1st- Crucifixion of the old man, (tortured for leaving the vices and the bad habits and sins).
2nd Until death (of human nature).
3rd And to be buried (forgotten).
4th For the resurrection of a new man, according to God´s Will (this is the baptism that Jesus said, to born again, and Paul confirmed, to resuscitate a new man).
Is one of the most important acts of

admission and decision for a grown person.The older Churches (Catholic, Lutheran, Presbyterian, Anglican and Methodist) transfer to a newly born, who can´t assume or decide anything. This is made to anarchize Christianism from the beginning.
There is no one verse where a child is baptized or anything that justifies this absurd. And there it divides, starting with Baptist, dozens multiply into thousands, condemning, with reason, child baptism, but make a mistake, condemning aspersion.
The immersionists affirm that the word baptism, in Greek, is to bury, this is a lie.
The word baptism, in Greek is the same as purification in Hebrew, and that it was sprinkled never submerged, like the immersionists affirm. Paul speaks in Greek. Texts that the theologians never wanted to understand, and that the Mormons, changed to baptized the dead. 1st Cor 15: