Baptismal

Ecclesiastical. a ceremonial immersion in water, or application of water, as an initiatory rite or sacrament of the Christian church.
any similar ceremony or action of initiation, dedication, etc.
a trying or purifying experience or initiation.
Christian Science. purification of thought and character.
Contemporary Examples

In my church’s baptismal Covenant, we promise to respect the dignity of every human being.
On Her Own Terms: Why Brittany Maynard Has Chosen to Die Gene Robinson October 11, 2014

In the early centuries of the Catholic Church, Bishops of Rome always retained their baptismal names while “in office.”
Can We Call Him Frank? New Pope Picks New Name, Francis Andrew Romano March 12, 2013

noun
a Christian religious rite consisting of immersion in or sprinkling with water as a sign that the subject is cleansed from sin and constituted as a member of the Church
the act of baptizing or of undergoing baptism
any similar experience of initiation, regeneration, or dedication
adj.

1640s, from baptism + -al (1).
n.

c.1300, bapteme, from Old French batesme, bapteme (11c., Modern French baptême), from Latin baptismus, from Greek baptismos, noun of action from baptizein (see baptize). The -s- restored in later 14c.

Figurative sense is from late 14c. The Anglo-Saxons used fulluht in this sense (John the Baptist was Iohannes se Fulluhtere). Phrase baptism of fire “a soldier’s first experience of battle” (1857) translates French baptême de feu; the phrase originally was ecclesiastical Greek baptisma pyros and meant “the grace of the Holy Spirit as imparted through baptism.” Later it was used of martyrdom, especially by burning.

The ceremony of initiation into Christianity; in most Christian churches, it is considered a sacrament. Persons baptized either have water poured on them or are immersed in water; some groups of Christians insist on immersion. The effect of baptism, in Christian belief, is to cleanse persons of their sins, so that they are born into a new life with Jesus. Most churches baptize members when they are infants, but some groups, like the Baptists, insist on adult baptism. Jesus himself was baptized. (See John the Baptist.)