The Coming of Jesus - The Descent of the Spirit on Him As The Sealing and Empowering of the King (1:9-11).
The preparations completed Jesus now comes to John to be baptised, in exactly the same way as the people had, and having been baptised the Holy Spirit comes on Him as the One Who is introducing the age of the Spirit. And at this point a voice from heaven says, ‘You are my beloved Son (Psalms 2:7), in you I am well pleased' (Isaiah 42:1). By this He is declared to be both God's Son and God's Servant. (Or alternately, ‘You are My Son, the Beloved in Whom I am well pleased' - compare Matthew 12:18).
Psalms 2 initially announces the acceptance of David's heirs as God's adopted sons (Mark 1:7, compare 2 Samuel 7:14), but it also has especially in mind the great king who is coming, His anointed one (Mark 1:2) who will establish his rule over the nations (Mark 1:8-9). Isaiah 42:1-4, along with Isaiah 49:1-6; Isaiah 50:4-8 and Isaiah 52:13 to Isaiah 53:12, has in mind the great Servant of the Lord who will bring about God's purposes through suffering.