Baptism is the foundation of the whole of Christian life. It is the gateway to life in the Holy Spirit and the door that gives access to the other sacraments. Baptism is a one-off event and anyone who has not previously been baptised may seek Baptism. Through Baptism a person is reborn as a daughter or son of God. It is through Baptism that an individual begins his or her formal relationship with Jesus Christ and the Church.
The phrase “to baptise” means to "plunge" or "immerse". The immersion in water, or alternatively the pouring of water over the person's head, symbolises the baptised person's union with the death of Jesus. Just as Christ was raised from the dead, the baptised person rises from the water as a "new creature", a member of the Church.
Baptism consists of a person's immersion in water three times or of the pouring of water over the person's head three times, with the recitation of the words, "I baptise you in the name of the Father, and of the Son, and of the Holy Spirit."
Those who have been validly baptised in another Christian tradition and are seeking to enter into full communion with the Catholic Church do not need to be baptised again.
Baptism in the history of the Church
From the very beginning of the Church, Baptism has been administered and celebrated as the means by which one becomes a Christian. Indeed, St Peter declares to the crowd on the day of Pentecost, "Repent, and be baptised every one of you in the name of Jesus Christ so that your sins may be forgiven; and you will receive the gift of the Holy Spirit" (Acts 2:38).
The first Christians baptised were adults. Then as entire families wanted to become followers of Christ, the rite of Baptism was adapted to cater for the children and infants of the baptised parents.
The forgiveness of sins
Through Baptism all sins are forgiven. As noted above, Baptism formalises the Christian's relationship with Jesus Christ. As this relationship grows, Jesus joins with and strengthens the person's own effort in living a full and joyful life and resisting temptation.
Integrated into the Church, the Body of Christ
Through Baptism, Christians are integrated into the Body of Christ, the Church. Membership of the Church is open to all, with no distinction of nationality, culture, race or gender.
A permanent relationship with Christ
Through Baptism, the Holy Spirit seals the Christian in a permanent relationship with Christ. The effects of sin may hinder the effects of Baptism, but sin cannot erase this sign of God's fidelity. It is for this reason that Baptism is received only once.
The ritual of Baptism includes such symbols as immersion in or pouring of water, anointing with blessed oil as a sign of being set apart, lighting a candle as a sign of Christ the light of the world and the putting on of a white robe as a sign of new life as a follower of Christ.
Extract from "Call and Response: An Introduction to the Catholic Faith" (76)