The Old Testament prefigures baptism in several ways. In the first Genesis account of creation, the Spirit overshadows the waters and brings life to the earth. In a similar way, today the Holy Spirit imparts new life at baptism. God used the Flood and Noah’s ark to purify the earth and bring about a new beginning. Today, Christ gives new life to the Christian who emerges from the baptismal waters. During the Exodus, God's Chosen People gained liberty from the Egyptian slave masters when they crossed the Red Sea. Similarly, baptism frees us from the slavery of sin. Finally, when the Israelites crossed the Jordan River into Canaan, they entered the Promised Land. When we pass through the waters of baptism, Jesus promises us eternal life in heaven.
The prefiguring of the sacrament of baptism in salvation history is completed in the ministry of Jesus Christ. His own baptism, totally unnecessary for the Sinless One, reveals his remarkable humility and marks the beginning of his public life. The Savior’s baptism looks forward to the sacrament he established and entrusted to his followers, for example, when he commanded his apostles to go out and preach the good news and to baptize in his name (Mt. 28:19-20). Jesus also spoke of his suffering and Passion as a “baptism” which he had to undergo for our benefit. The water and blood that gushed from his side at the time of his death make it possible for us "to be born again of water and the Spirit."
The Church has initiated new Christians through Baptism since the first Pentecost, when over 3,000 were baptized. It is through our own baptism that we are united into Christ’s death, burial, and resurrection.