I’m reading a book with tons of good information on Christian beginnings; early practices, first leadership, and the like. One interesting section deals with baptism. Early Christian baptism was something of a drawn-out affair- really an initiation. Those wishing for baptism in the 200’s had to go through a three year trial period in during which they were scrutinized for good behavior. Certain professionals were denied outright: actors, governors, magicians, and prostitutes. Near the end of the three years, initiates would be exorcised daily by laying on of hands. The day before baptism was to take place, they fasted and held an all-night vigil. Then at dawn they would head to the spring. Those getting baptized removed their clothes and got anointed with oil for another exorcism. Then a deacon washed them each three times for all three parts of the trinity. One more dose of oil for thanksgiving, and the baptism was complete.
Adults were most commonly baptized, but kids too sometimes joined. Cyprian was pro-infant baptism. He seemed to think it would help new babies stay away from sin. Tertullian was anti-infant baptism. To him, baptism was far too serious a choice for someone else to make for you. He even worried that parents and sponsors might bring damnation on themselves if the child grew up to reject the baptism.
For early Christians, baptism differed from other cult initiations in that it was considered universal. If one was baptized in a Christian church, that baptism stood for every church he might visit. Pagan groups generally required re-initiation into the local chapter.