Baptism is a Christian sacrament of initiation and adoption, almost invariably with the use of water. It may be performed by sprinkling or pouring water on the head, or by immersing in water either partially or completely, traditionally three times, once for each person of the Trinity. The synoptic gospels recount that John the Baptist baptised Jesus. Baptism is considered a sacrament in most churches, and as an ordinance in others. 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. Baptism is also called christening, although some reserve the word "christening" for the baptism of infants. 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.
Infant baptism is the practice of baptizing infants or young children. Infant baptism is also called christening by some faith traditions.
Religious conversion is the adoption of a set of beliefs identified with one particular religious denomination to the exclusion of others. Thus "religious conversion" would describe the abandoning of adherence to one denomination and affiliating with another. This might be from one to another denomination within the same religion, for example, from Protestant Christianity to Roman Catholicism or from Sunnī Islam to Shīʿa Islam. In some cases, religious conversion "marks a transformation of religious identity and is symbolized by special rituals".
Apostasy is the formal disaffiliation from, abandonment of, or renunciation of a religion by a person. It can also be defined within the broader context of embracing an opinion that is contrary to one's previous religious beliefs. One who undertakes apostasy is known as an apostate. Undertaking apostasy is called apostatizing. The term apostasy is used by sociologists to mean the renunciation and criticism of, or opposition to, a person's former religion, in a technical sense, with no pejorative connotation.
In Christian denominations that practice infant baptism, confirmation is seen as the sealing of the covenant created in baptism. Those being confirmed are known as confirmands. For adults, it is an affirmation of belief. It involves laying on of hands.
A lapsed Catholic is a Catholic who is non-practicing. Such a person may still identify as a Catholic, and remains one according to Catholic canon law.
A unity candle is a candle used in a wedding ceremony to symbolize two people joining in marriage.
Catechesis is basic Christian religious education of children and adults, often from a catechism book. It started as education of converts to Christianity, but as the religion became institutionalized, catechesis was used for education of members who had been baptized as infants. As defined in the Catechism of the Catholic Church, paragraph 5 :
Catechesis is an education in the faith of children, young people and adults which includes especially the teaching of Christian doctrine imparted, generally speaking, in an organic and systematic way, with a view to initiating the hearers into the fullness of Christian life.
Apostasy in Christianity is the repudiation of Christ and the central teachings of Christianity by someone who formerly was a Christian (Christ-follower). The term apostasy comes from the Greek word apostasia meaning "rebellion", "state of apostasy", "abandonment", or "defection". It has been described as "a willful falling away from, or rebellion against, Christianity. Apostasy is the rejection of Christ by one who has been a Christian. …" "Apostasy is a theological category describing those who have voluntarily and consciously abandoned their faith in the God of the covenant, who manifests himself most completely in Jesus Christ." "Apostasy is the antonym of conversion; it is deconversion."
Feeneyism is a Christian doctrine, associated with Leonard Feeney, which advocates an interpretation of the dogma extra Ecclesiam nulla salus which is that only Catholics can go to heaven and that only those baptised with water can go to heaven. Feeneyism opposes the doctrines of baptism of desire and baptism of blood as well as the view that non-Catholics can go to heaven.
Renunciation is the act of rejecting something, particularly something that the renunciant has previously enjoyed or endorsed.
Religious disaffiliation is the act of leaving a faith, or a religious group or community. It is in many respects the reverse of religious conversion. Several other terms are used for this process, though each of these terms may have slightly different meanings and connotations.
In the canon law of the Catholic Church, an impediment is a legal obstacle that prevents a sacrament from being performed either validly or licitly or both. The term is used most frequently in relationship to the sacraments of Marriage and Holy Orders. Some canonical impediments can be dispensed by the competent authority as defined in Catholic canon law.
A schism is a division between people, usually belonging to an organization, movement, or religious denomination. The word is most frequently applied to a split in what had previously been a single religious body, such as the Great East–West Schism or the Western Schism. It is also used of a split within a non-religious organization or movement or, more broadly, of a separation between two or more people, be it brothers, friends, lovers, etc.
An emergency baptism is a baptism administered to a person in danger of death. This can be done by a person not normally authorized to administer the sacraments.
A formal act of defection from the Catholic Church was an externally provable juridic act of departure from the Catholic Church that existed between 1983 and 2010.
Heresy is any belief or theory that is strongly at variance with established beliefs or customs, particularly the accepted beliefs or religious law of a religious organization. A heretic is a proponent of heresy.
Believer's baptism or adult baptism 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.
In the canon law of the Catholic Church, excommunication is a form of censure. In the formal sense of the term, excommunication includes being barred not only from the sacraments but also from the fellowship of Christian baptism. The principal and severest censure, excommunication presupposes guilt; and being the most serious penalty that the Catholic Church can inflict, it supposes a grave offense. The excommunicated person is considered by Catholic ecclesiastical authority as an exile from the Church, for a time at least.
The Order of Christian Initiation of Adults (Latin: Ordo initiationis christianae adultorum), or OCIA, is a process developed by the Catholic Church for its catechumenate for prospective converts to the Catholic faith above the age of infant baptism. Candidates are gradually introduced to aspects of Catholic beliefs and practices. The basic process applies to adults and children who have reached catechetical age. Previously, the OCIA was known as the Rite of Christian Initiation of Adults (RCIA). The English name of the process was changed by the United States Conference of Catholic Bishops in 2021 to reflect greater fidelity to the original Latin, although this change has yet to be officially approved by the Dicastery for Divine Worship and the Discipline of the Sacraments.
