In this verse and the next we see the Trinity operating together in perfect agreement: the incarnate Son is baptized and ready to begin his public ministry; the Spirit of God come down visibly from heaven to remain on him throughout his earthly ministry, and the Father testifies to the perfect obedience of the Son which fills him with pleasure. All the focus is on the Son, the member of the godhead who is to carry out the work of redemption on earth, and who is the mediator between God and man.
Why was Christ given the Spirit? John’s Gospel records the words of John the Baptist: ‘He whom God hath sent speaketh the words of God: for God giveth not the Spirit by measure unto him’ (John 3:34). Hendriksen says, ‘It should be constantly borne in mind that, though Christ’s divine nature was not in need of, and was in fact incapable of, being strengthened, the same was not true with respect to his human nature. This could be, and needed to be, strengthened.’
Any suggestion that Christ was a man who only became divine at his baptism is refuted by clear statements of Scripture about the one who was conceived in Mary’s womb and born to her. At the beginning it was said to her ‘that holy thing which shall be born of thee shall be called the Son of God’ (Luke 1:35).