Catholic
The Catholic Church teaches that baptism is the first sacrament, by which a person is freed from sin, reborn as a child of God, and incorporated into Christ and his Church. It holds that baptism is necessary for salvation, washes away original sin, and imprints an indelible spiritual mark.
Source: CCC 1213–1228; 1257; 1263; 1272 ↗
Orthodox
The Orthodox Church teaches that baptism — by triple immersion in the name of the Trinity — is the mystery of new birth, washing away sin and uniting the believer to Christ's death and resurrection. It holds that infants are baptized into the faith of the Church, followed immediately by chrismation and communion.
Source: The Orthodox Faith, Vol. II — Baptism ↗
Lutheran
Lutherans teach that baptism is necessary for salvation and that through it God's grace is offered, faith is worked, and infants are regenerated. They hold that baptism is not mere water but water comprehended in God's command and connected with his Word, effective because of the Word, not the water.
Source: Augsburg Confession, Art. IX; Small Catechism, Holy Baptism ↗
Reformed
The Reformed tradition teaches that baptism is a sign and seal of the covenant of grace — of ingrafting into Christ, regeneration, and remission of sins. It holds that the infants of professing believers are to be baptized, and that the efficacy of baptism belongs to the elect in God's appointed time.
Source: Westminster Confession 28.1–28.6 ↗
Baptist
Baptists teach that Christian baptism is the immersion of a believer in water in the name of the Father, Son, and Holy Spirit. They hold that it is an act of obedience symbolizing the believer's death to sin and resurrection to new life — a testimony of faith; in the Baptist understanding, a symbolic act rather than a means of conveying saving grace.
Source: BFM 2000, VII ↗
Methodist
Methodists teach that baptism is the sacrament of initiation into Christ's holy Church, a sign of God's prevenient grace and of new birth. They practice infant baptism as well as believer's baptism, holding that God's grace precedes and enables the human response of faith.
Source: Articles of Religion, Art. XVII; UMC What We Believe ↗