The Catechism of the Catholic Church tells us that "Holy Baptism is the basis of the whole Christian life, the gateway to life in the Spirit (vitae spiritualis ianua), and the door which gives access to the other sacraments. Through Baptism, we are freed from sin and reborn as sons of God; we become members of Christ, are incorporated into the Church and made sharers in her mission." (CCC 1213) Baptism is the beginning of Christian life. It restores us to right relationship with God, wiping away the stain of original sin.
In the Catholic tradition, adults who enter the Church do so at the Easter Vigil. Gathered with the entire Church to celebrate Christ's resurrection and victory over sin, we then welcome our newfound catechumens or candidates into the fullness of life in the Church. Baptism then makes them part of the community, part of the family of God. Followed by the other Sacraments of Initiation, they join in Holy Communion and are Confirmed and strengthened by the Holy Spirit to journey forth as disciples of Christ.
Catholics also believe in infant Baptism. Just as our spiritual brothers in Judaism circumcise their children on the 8th day, Catholics offer their children to God through Baptism shortly after birth. It is through this act that we hope to consecrate and strengthen our children as they grow as part of the family of God. It is through this that we attempt to fulfill the mandate of Christ himself as he declared that His Church should "make disciples of all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Spirit."