Holy Baptism is the basis of the whole Christian life, the gateway to life in the Spirit, 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 are made sharers in her mission. "Baptism is the sacrament of regeneration through water and in the word."
(Catechism of the Catholic Church #1213)