Christian Baptism has its origin and foundation in Jesus. Jesus began his public ministry by being baptized by John the Baptist, and after his resurrection gave his apostles the mission to “Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit” (Mt 28:19). He further explains that “whoever believes and is baptized will be saved” (Mk 16:16).
From the beginning the Church has fulfilled the Lord’s commission to baptize. As the Catechism states, “From the very day of Pentecost, the Church has celebrated and administered holy Baptism. Indeed St. Peter declares to the crowd astounded by his preaching: “Repent, and be baptized every one of you” (CCC, 1226; Acts 2:38). This invitation continues today as the Church offers all entrance into life in the Spirit through the waters of Baptism.
United States Catholic Catechism for Adults: http://ccc.usccb.org/flipbooks/uscca/#208
Catholic Answers: http://www.catholic.com/tracts/the-necessity-of-baptism
Fr. Robert Barron: http://www.wordonfire.org/resources/video/the-sacrament-of-baptism/276/