Definition of Baptism
The Roman Catechism (Ad parochos, De bapt., 2, 2, 5) defines baptism thus:
Baptism is the sacrament of regeneration by water in the word (per aquam in
verbo). St. Thomas Aquinas (III:66:1) gives this definition: “Baptism
is the external ablution of the body, performed with the prescribed form of
Later theologians generally distinguish formally between the physical and the
metaphysical defining of this sacrament. By the former they understand the
formula expressing the action of ablution and the utterance of the invocation
of the Trinity; by the latter, the definition: “Sacrament of
regeneration” or that institution of Christ by which we are reborn to
The term “regeneration” distinguishes baptism from every other
sacrament, for although penance revivifies men spiritually, yet this is
rather a resuscitation, a bringing back from the dead, than a rebirth.
Penance does not make us Christians; on the contrary, it presupposes that we
have already been born of water and the Holy Ghost to the life of grace,
while baptism on the other hand was instituted to confer upon men the very
beginnings of the spiritual life, to transfer them from the state of enemies
of God to the state of adoption, as sons of God.
The definition of the Roman Catechism combines the physical and metaphysical
definitions of baptism. “The sacrament of regeneration” is the
metaphysical essence of the sacrament, while the physical essence is
expressed by the second part of the definition, i.e. the washing with water
(matter), accompanied by the invocation of the Holy Trinity (form). Baptism
is, therefore, the sacrament by which we are born again of water and the Holy
Ghost, that is, by which we receive in a new and spiritual life, the dignity
of adoption as sons of God and heirs of God's kingdom.
Written by William H.W. Fanning. Transcribed by Charles Sweeney, S.J..
The Catholic Encyclopedia, Volume II. Published 1907. New York: Robert
Appleton Company. Nihil Obstat, 1907. Remy Lafort, S.T.D., Censor.
Imprimatur. +John M. Farley, Archbishop of New York