Mark wastes no time in his gospel. Immediately, Mark wants us to know who he understands Jesus to be. The first eleven verses of Mark's gospel are jammed pack with Christology. Mark is presenting Jesus to us as the Spirit-filled Messiah, even the presence of God himself, who will deliver Israel from its exile.
The most explicit statement about Jesus is probably the one verse introduction of the gospel in which Jesus is descibed as Christ (which means Messiah) and the Son of God. However, in the following verses Mark continues to present Jesus as the Christ in more subtle and symbolic ways. This is true especially of the quotations from Isaiah and Malachi in verses 2 and 3 which Mark clearly uses to desribe John the baptist as the one who is preparing the way for the Lord, Yahweh, the God of Israel(You can read more about the quotation from Isaiah here.) The fascinating thing is that immediately after John the baptist finishes talking about the mighty one who will come after him, Mark inserts Jesus into the scene. Thus Mark presents Jesus as Yahweh himself, the one for whom John was preparing the way.
The barrage of Christology then continues with the short, two-verse description of Jesus' baptism. As Jesus comes up out of the water the heavens are torn apart (possibly a reference to Isaiah 64:1?), the Spirit descends upon Jesus like a dove, and a voice declares from heaven "You are my beloved Son, in You I am well-pleased." Only eleven verses into Mark's gospel, there can be little doubt for Mark's audience that he intends to present Jesus as God's Spirit-filled agent of deliverance.
It was how Jesus would accomplish that deliverance that would have been scandalous to Jesus' contemporaries and a continual challenge for Mark's audience. But Mark makes an intentional link between his presentation of Jesus as Messiah and his death on the cross. Mark places three literary parallels to Jesus' baptism in his description of Jesus' crucifixion. First, the curtain temple is torn in two from top to bottom at Jesus' death just as the heavens are torn open at his baptism (these are the only two places this word is used in all of Mark's gospel). Second, the centurion who is standing in front of Jesus says "Truly this man was the Son of God!" echoing the voice from heaven at Jesus' baptism. Finally, Mark 15:37 says that Jesus breathed his last. In English, this has no apparent connection to the baptism passage but this Greek word is a combination of a preposition and the word for spirit. Read very literally, it says that Jesus "spirited-out", thus linking his death once again to his baptism when the Spirit first descended upon Jesus in Mark's gospel.
This has at least two imporant consequences for our understanding of Jesus, the Spirit, and the Church. The first is that Jesus' presentation as Messiah, deliverer, and Son of God can not be separated from his crucifxion. It's not that his crucifixion made him these things. After all, the Spirit descended upon him long before his crucifixion. However, it is to say that the all-powerful and glorious God of all creation has forever linked himself to the shame and profanity of the cross. We can not know the resurrected king of glory without knowing the peasant crucified as a rebel.
Secondly, the "bookends" of Mark's gospel communicate to us that the Spirit of God has been poured out on creation, let loose in the world. The Spirit of Yahweh which dwelt in the temple, the same Spirit which rested on Jesus and empowered him throughout his ministry, has now been breathed out by Jesus and ripped out of its place through the Temple curtain. That Spirit now rests on Jesus' disciples, empowering us to continue the same minsitry that he began.