Immersion, Affusion, and the Centuries Between

Baptism's earliest form was full immersion in living water, following the model of John the Baptist at the Jordan and continued by the first Christian communities, who distinguished their washing from Jewish purification bathing by tying it to the death and resurrection of Jesus rather than to ritual defilement. The book of Acts shows converts baptised immediately on profession of faith, often in rivers or cisterns, with no fixed liturgy beyond invoking the divine name. By the second and third centuries a longer catechumenate had developed, weeks or years of instruction before baptism was granted, usually reserved for the Easter vigil.

As Christianity moved into colder regions and into buildings without rivers, affusion, pouring water over the head, and later aspersion, sprinkling, became accepted substitutes for full immersion, a change the early text called the Didache already permits when water is scarce. The font itself evolved from open pools to the small basins familiar today.

Eastern Orthodox and many Baptist and Pentecostal churches kept or later revived full immersion as the norm, arguing it alone pictures burial and rising, while most Western churches settled on pouring for practical and pastoral reasons rather than doctrinal ones. The rite's minister also changed over time: early baptism could be performed by any believer in an emergency, a permission Catholic canon law still preserves for danger of death.