Affusion in the context of Drowning

Baptism (from Koine Greek: βάπτισμα, romanized: váptisma, lit. 'immersion, dipping in water') is a Christian rite of initiation almost invariably with the use of water. It may be performed by sprinkling or pouring water on the head, or immersing in water (partially or completely), traditionally three times for each person of the Trinity. It is also called christening, although this is typically reserved for the baptism of infants. Baptism is regarded as a sacrament in most churches and an ordinance in others, with the synoptic gospels recounting that John the Baptist baptized Jesus.

Baptism according to the Trinitarian formula, which is done in most mainstream Christian denominations, is seen as being a basis for Christian ecumenism, the concept of unity amongst Christians. In certain Christian denominations, such as the Catholic Churches, Eastern Orthodox Churches, Oriental Orthodox Churches, Assyrian Church of the East, and Lutheran Churches, baptism is the door to church membership, with candidates taking baptismal vows. It has also given its name to the Baptist churches and denominations.

Aspersion (la. aspergere/aspersio), in a religious context, is the act of sprinkling with water, especially holy water. Aspersion is a method used in baptism as an alternative to immersion or affusion. The word is formed of the Latin aspergere, 'to sprinkle', of ad, 'to', and spargo, 'I scatter' (Ezekiel 36:25–26, 1 Corinthians 10:2, cf. Psalm 77:16-20).

In addition, aspersion is performed as part of certain rites to remind people of their baptism, such as the renewal of baptismal vows performed by the Catholic Church and Lutheran Church at Easter.

Immersion baptism (also known as baptism by immersion or baptism by submersion) is a method of baptism that is distinguished from baptism by affusion (pouring) and by aspersion (sprinkling), sometimes without specifying whether the immersion is total or partial, but very commonly with the indication that the person baptized is immersed in water completely. The term is also, though less commonly, applied exclusively to modes of baptism that involve only partial immersion (see Terminology, below).

Believer's baptism (also called credobaptism, from the Latin word credo meaning "I believe") is the practice of baptizing those who are able to make a conscious profession of faith, as contrasted to the practice of baptizing infants. Credobaptists believe that infants incapable of consciously believing should not be baptized.

The mode of believer's baptism depends on the Christian denomination, and is done either by pouring (the normative method in Mennonite, Amish, and Hutterite churches) or by immersion (the normative method practiced by Schwarzenau Brethren, River Brethren, Baptists, and the Churches of Christ, among others). Among those denominations that practice immersion, the way that it is practiced depends on the Church; the Schwarzenau Brethren and the River Brethren for example teach "trine immersion, that is, dipping three times forward in the name of the Father, the Son, and the Holy Spirit."

The Didache (/ˈdɪdəkeɪ, -ki/; Ancient Greek: Διδαχή, romanized: Didaché, lit. 'Teaching'), also known as The Lord's Teaching Through the Twelve Apostles to the Nations (Διδαχὴ Κυρίου διὰ τῶν δώδεκα ἀποστόλων τοῖς ἔθνεσιν, Didachḕ Kyríou dià tō̂n dṓdeka apostólōn toîs éthnesin), is a brief anonymous early Christian treatise (ancient church order) written in Koine Greek, dated by modern scholars to the first or (less commonly) second century AD.

The first line of this treatise is: "The teaching of the Lord to the Gentiles (or Nations) by the twelve apostles". The text, parts of which constitute the oldest extant written catechism, has three main sections dealing with Christian ethics, rituals such as baptism and Eucharist, and Church organization. The opening chapters describe the virtuous Way of Life and the wicked Way of Death. The Lord's Prayer is included in full. Baptism is by immersion, or by affusion if immersion is not practical. Fasting is ordered for Wednesdays and Fridays. Two primitive Eucharistic prayers are given. Church organization was at an early stage of development. Itinerant apostles and prophets are important, serving as "chief priests" and possibly celebrating the Eucharist; meanwhile, local bishops and deacons also have authority and seem to be taking the place of the itinerant ministry.