Why do Catholics baptise?

Jesus is baptised by John in the Jordan; the Spirit comes down like a dove and the voice of the Father says: this is my beloved Son.

Jesus tells Nicodemus that no one can enter the Kingdom of God without being born of water and the Spirit.

Before the Ascension, Jesus sends the apostles to make disciples of all nations, baptising them in the name of the Father, the Son and the Holy Spirit.

At Pentecost Peter says: repent and be baptised, every one of you, for the forgiveness of your sins, and you shall receive the gift of the Holy Spirit.

Paul writes that in baptism we are buried with Christ, so that we may rise with him to a new life, and that those who are baptised have put on Christ.

In Acts, whole households are baptised: Lydia's household, and the household of the jailer at Philippi.

The Didache, from the late 1st or early 2nd century, asks that baptism be done in running water, or, if there is none, by pouring water three times on the head in the name of the Father, the Son and the Holy Spirit.

In the first centuries, adults prepared for a long time and were baptised at the Easter Vigil. They were then dressed in white and received a lit candle, gestures still kept today.

From at least the 3rd century, Christian writers speak of baptising children. Some historians think the household baptisms in Acts already included them; others disagree.

Early churches built separate baptisteries, often eight-sided: the eighth day, the day after the sabbath, was a symbol of the Resurrection and new creation.

At the start of the celebration, the sign of the cross marks the person with the imprint of Christ, who redeemed us by his Cross.

Baptism is the basis of the whole Christian life, the gateway to life in the Spirit and the door to the other sacraments.

Baptism forgives original sin and all personal sins, and imprints an indelible spiritual mark, so it is never repeated.

By baptism the Christian has already died with Christ sacramentally, in order to live a new life.

In case of necessity, anyone, even someone who is not baptised, can baptise, by pouring water and saying the Trinitarian formula with the intention of doing what the Church does.