9 At that time Jesus came from Nazareth in Galilee and was baptized by John in the Jordan. 10 Just as Jesus was coming up out of the water, he saw heaven being torn open and the Spirit descending on him like a dove. 11 And a voice came from heaven: "You are my Son, whom I love; with you I am well pleased." 12 At once the Spirit sent him out into the wilderness, 13 and he was in the wilderness forty days, being tempted by Satan. He was with the wild animals, and angels attended him. 14 After John was put in prison, Jesus went into Galilee, proclaiming the good news of God. 15 "The time has come," he said. "The kingdom of God has come near. Repent and believe the good news!"
John Calvin: Here John could see something beyond the planets and stars. The words in Mark can have no other meaning, he saw the heavens cleft asunder. It is not important to know how this happened, as much as we recognize it was a symbol of the Divine Presence. John and Christ received some additional certainty about Christ's calling here. The Holy Spirit came upon Jesus here as he began his public ministry now. Isaiah 61:1 (The Spirit of the Lord is upon me, for he has anointed me to preach good news to the poor...) indicates that when he began to discharge his duties as Redeemer, the Spirit came in power- not just for himself but for all. Baptism is tied to the Gospel and so baptism began when Christ was preparing to preach the Gospel. The Spirit descended not as fire but as a dove- for Christ's ministry was mild and gentle (Isa. 42:2,3), so we may not fear to approach Christ. How could John see the Spirit? The Spirit is everywhere and did not descend in a literal sense. John did not see the essence of the Spirit but a manifestation of the Spirit.
The baptism of Christ was in order to please- well the Father. So it is with our baptism. Baptism is not a human ordinance, but a God-given sacrament. After his anointing in the wilderness, he left John to be tempted in the wilderness. The good news, is that even in this state of total isolation for forty days (as Moses), the angels attended him. Christ has a tough row to hoe, and being tempted probably firmed up his resolve. Christ continued John's ministry when John himself could not continue it- as he was in prison. It was clear to John that his ministry was not fruitless, for Jesus enhanced it.