The Greek word for the rite of baptism means ‘to dip in’ or ‘to wash’ but the classical meaning of drowning or overwhelming is found in the LXX (Isa. 21: 4), and there is a suggestion of this sense in the NT when Jesus predicts his coming ‘baptism’ of death (Mark 10: 38–9) and perhaps when Paul refers to the Israelites being ‘baptized’ in the Red Sea (1 Cor. 10: 2). Both these passages are interpretations of Christian baptism; for Paul baptism is compared to Israel's Exodus through the sea; and in baptism Christians share symbolically in Jesus' death and resurrection; they are buried with him and rise to a new life. So baptism is also regarded as the beginning of a new life (John 3: 4–5).

The Christian rite was not without some partial precedents in Judaism and in other religions. Water is a natural and vivid source of purification, so Gentiles who wished to become Jews baptized themselves before circumcision. At Qumran there were elaborate rites of purification by water. John the Baptist invited his hearers to repent and to be baptized in the River Jordan, and Jesus accepted baptism at his hands, not for remission of sins (Matt. 3: 13–15) but to identify himself with his people. It was the moment when he was commissioned to proclaim the kingdom, the moment when he was adopted as Son of God (Mark 1: 10–11).

Baptism immediately assumed the role of rite of initiation into the covenant which had been, and is, the purpose of circumcision in Judaism (Col. 2: 11–12). Peter exhorted his audience in Jerusalem to repent and accept baptism (Acts 2: 38). An Ethiopian eunuch was baptized, without an elaborate course of instruction, by Philip as soon as there was a handy pool of water (Acts 8: 38). It is not recorded that the Ethiopian became a member of a local Christian community ‘but he went on his way rejoicing’, a fruit of the spirit (Gal. 5: 22).

It was held that in baptism the gift of the Spirit was conferred, as it had been with Jesus (Mark 1: 10), and the prerequisite for baptism was faith (Gal. 3: 14). Whether the requirement of faith therefore excludes infants from the Christian sacrament is much debated; there is no explicit evidence either way in the NT. It is argued that households who were baptized (Acts 16: 15, 33) would have included infants; and the parallel with circumcision as a rite of infant initiation points in the same direction.

Archaeological evidence from the early centuries shows that baptism was administered sometimes by submersion or immersion, in which the rite symbolically re-enacted the process of burial and resurrection, but also by affusion from a vessel when water was poured on the candidate's head, just as earth was sprinkled over the corpse at a funeral. There is a similarity of symbolism in both forms of ritual. Paul mentions a practice in his time of baptism ‘on behalf of the dead’ (1 Cor. 15: 29). He is referring, perhaps, to those at Corinth who were baptized with a view to being united at the resurrection with their Christian friends who had died.

In addition to the use of water, the Apostolic Tradition of Hippolytus mentions anointings, following the OT practice of anointing the high priest (Exod. 29: 7; 30: 25). Other aspects of the OT rite are present in baptism—forgiveness of sins, putting on a new nature (Col. 3: 10), and being called out of darkness into light as the royal priesthood (1 Pet. 2: 9).