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Meaning and effects

There are differences in views about the effect of baptism for a Christian. Catholics, Orthodox, and most mainline Protestant groups assert baptism is a requirement for salvation and a sacrament, and speak of " baptismal regeneration ". Its importance is related to their interpretation of the meaning of the "Mystical Body of Christ" as found in the New Testament. This view is shared by the Catholic and Eastern Orthodox denominations, and by churches formed early during the Protestant Reformation such as Lutheran and Anglican. For example, Martin Luther said:

To put it most simply, the power, effect, benefit, fruit, and purpose of Baptism is to save. No one is baptized in order to become a prince, but as the words say, to "be saved". To be saved, we know, is nothing else than to be delivered from sin, death, and the devil and to enter into the kingdom of Christ and live with him forever.

The Churches of Christ," Jehovah's Witnesses, Christadelphians, and The Church of Jesus Christ of Latter-day Saints espouse baptism as necessary for salvation.

For Roman Catholics, baptism by water is a sacrament of initiation into the life of the children of God (Catechism of the Catholic Church, 1212–13). It configures the person to Christ (CCC 1272), and obliges the Christian to share in the church's apostolic and missionary activity (CCC 1270). The Catholic holds that there are three types of baptism by which one can be saved: sacramental baptism (with water), baptism of desire (explicit or implicit desire to be part of the church founded by Jesus Christ), and baptism of blood (martyrdom). In his encyclical Mystici corporis Christi of June 29, 1943, Pope Pius XII spoke of baptism and profession of the true faith as what makes members of the one true church, which is the body of Jesus Christ himself, as God the Holy Spirit has taught through the Apostle Paul:

By contrast, Anabaptist and Evangelical Protestants recognize baptism as an outward sign of an inward reality following on an individual believer's experience of forgiving grace. Reformed and Methodist Protestants maintain a link between baptism and regeneration, but insist that it is not automatic or mechanical, and that regeneration may occur at a different time than baptism. Churches of Christ consistently teach that in baptism a believer surrenders his life in faith and obedience to God, and that God "by the merits of Christ's blood, cleanses one from sin and truly changes the state of the person from an alien to a citizen of God's kingdom. Baptism is not a human work; it is the place where God does the work that only God can do." Thus, they see baptism as a passive act of faith rather than a meritorious work; it "is a confession that a person has nothing to offer God".