On the first Sunday of Advent we heard the prophet Isaiah beseeching God, 'Oh that you would tear the heavens and come down.' Now six weeks later, on this last day of the Christmas season, we see one of the ways in which this prayer is answered.
In the Gospel for today the heavens are torn open and God 'comes down,' in the form of a dove, in the voice of the Father and the person of Jesus. This sudden tearing of the heavens fits in well with the fast pace and startling appearance of Jesus and John the Baptist in Mark's Gospel.
The intensity, and density, of the scene is concentrated even more when we consider the resonances of the place and imagery.
The place is the river Jordan which had great significance for the people of Israel. It is the liminal place, the borderland, between the desert and the Promised Land. The last time someone called Jesus passed through the Jordan it was to lead the people of Israel into the land flowing with milk and honey. What Moses could not ultimately do, Joshua did.
What Jesus, the new Joshua, does is even greater. Joshua in the Old Testament led the people in a 'horizontal' movement into an earthly, temporary Promised Land. Jesus opens up the 'vertical' way into the eternal Promised Land of sharing the life of the Trinity for all eternity. God tears open the heavens to show us who Jesus is and why we should follow him down into the waters of baptism and the darker waters of death.
As the Catechism puts it
At his baptism 'the heavens were opened' -- the heavens that Adam's sin had closed -- and the waters of baptism were sanctified by the descent of Jesus and of the spirit, a prelude to the new creation (CCC 536).
The Holy Spirit descends on the waters in the form of a dove. This, of course, recalls the opening of the sacred scriptures, the very beginning of creation, when the spirit of God 'hovers' over the chaos waters (Gen 1:2). Here, at the beginning of Mark's Gospel, creation is being renewed and redeemed by the Son of God going down into the waters as the Spirit hovers again.
So this feast is a prelude to the new creation and the beginning of Jesus's public, adult mission. There is also a link with the later Transfiguration of Jesus. At the beginning of his public life was the baptism, an act of loving obedience to the Father and a revelation of the Trinity. Just before Jesus goes up to Jerusalem to suffer the Passion, another act of loving obedience to the Father, the Trinity is again revealed to the disciples, and the continuity between Jesus and the Law and the Prophets is demonstrated.
At these two crucial moments in the public life of Jesus his unity with the Father and the Spirit is revealed. At the baptism, he descends to the lowest depths of the earth; at the Transfiguration he ascends the mountain of the Lord, showing us the depth and height of God's love who fills all things.
We ourselves are drawn into this life of the Trinity by our own baptism. Our participation in the great Paschal mystery is given to us primarily through the gift of faith and the sacraments, instituted by Christ to conform us more closely to his life, death and resurrection. Christ makes the importance of baptism especially clear after his resurrection, when he tells the disciples:
All authority in heaven and earth has been given to me. Go therefore and make disciples of all nations, baptizing them in the name of the father, and of the Son and of the Holy Spirit, teaching them all I have commanded you; and lo, I am with you always, even to the close of the age (Matt 28:18-20).
So Christ's own baptism inaugurates the great work of preaching the Gospel to all the nations. This the Church has done and continues to do. Historically, through human weakness and sin her children have sometimes been too timid or zealous in inappropriate ways. However, the Church has the great and solemn assurance of the presence of Christ and the guidance of the Holy spirit, 'even to the close of the age.'