John’s sacrament was baptism, which is a cleansing ritual intended to wash away sins. To avoid reference to current Christian sects I prefer the translation “John the baptizer.” But this was standard practice in various forms: Pilate’s washing his hands of guilt in Jesus’ sentencing partakes of the same principle, and the emperor Claudius wrote a treatise on Roman lustral rituals. It’s a Christian conceit that the cleansing strips away the old self and results in a rebirth paralleing the Resurrection, an idea that has entered into psychedelic thought.