42 What are the elements of baptism which introduce us into this new "standard of teaching"? First, the name of the Trinity — the Father, the Son and the Holy Spirit — is invoked upon the catechumen. Thus, from the outset, a synthesis of the journey of faith is provided. The God who called Abraham and wished to be called his God, the God who revealed his name to Moses, the God who, in giving us his Son, revealed fully the mystery of his Name, now bestows upon the baptized a new filial identity. This is clearly seen in the act of baptism itself: immersion in water. Water is at once a symbol of death, inviting us to pass through self-conversion to a new and greater identity, and a symbol of life, of a womb in which we are reborn by following Christ in his new life. In this way, through immersion in water, baptism speaks to us of the incarnational structure of faith. Christ’s work penetrates the depths of our being and transforms us radically, making us adopted children of God and sharers in the divine nature. It thus modifies all our relationships, our place in this world and in the universe, and opens them to God’s own life of communion. This change which takes place in baptism helps us to appreciate the singular importance of the catechumenate — whereby growing numbers of adults, even in societies with ancient Christian roots, now approach the sacrament of baptism — for the new evangelization. It is the road of preparation for baptism, for the transformation of our whole life in Christ. To appreciate this link between baptism and faith, we can recall a text of the prophet Isaiah, which was associated with baptism in early Christian literature: "Their refuge will be the fortresses of rocks… their water assured" ( Is 33:16). The baptized, rescued from the waters of death, were now set on a "fortress of rock" because they had found a firm and reliable foundation. The waters of death were thus transformed into waters of life. The Greek text, in speaking of that water which is "assured", uses the word pistós, "faithful". The waters of baptism are indeed faithful and trustworthy, for they flow with the power of Christ’s love, the source of our assurance in the journey of life.
Source: Lumen Fidei (Vatican.va)