There were or are some protestant groups who once believed that Jesus did not become God until he was baptized and the Holy Ghost came down upon Him on this day. However these are a minority.
Saturday, the Church celebrates the Solemnity of the Baptism of Our Lord. This brings to an end the season of Christmas. The Church recalls Our Lord’s second manifestation or epiphany which occurred on the occasion of His baptism in the Jordan. Jesus descended into the River to sanctify its waters and to give them the power to beget sons of God. The event takes on the importance of a second creation in which the entire Trinity intervenes.
In the Eastern Church this feast is called Theophany because at the baptism of Christ in the River Jordan God appeared in three persons. The baptism of John was a sort of sacramental preparatory for the Baptism of Christ. It moved men to sentiments of repentance and induced them to confess their sins. Christ did not need the baptism of John. Although He appeared in the “substance of our flesh” and was recognized “outwardly like unto ourselves,” He was absolutely sinless and impeccable. He conferred upon the water the power of the true Baptism which would remove all the sins of the world: “Behold the Lamb of God, behold Him Who takes away the sin of the world.”
Many of the incidents which accompanied Christ’s baptism are symbolical of what happened at our Baptism. At Christ’s baptism the Holy Spirit descended upon Him; at our Baptism the Trinity took its abode in our soul. At His baptism Christ was proclaimed the “Beloved Son” of the Father; at our Baptism we become the adopted sons of God. At Christ’s baptism the heavens were opened; at our Baptism heaven was opened to us. At His baptism Jesus prayed; after our Baptism we must pray to avoid actual sin.
— Excerpted from Msgr. Rudolph G. Bandas