So far, we have heard the account of the Evangelist Luke, who presents Jesus who remained hidden in the crowd while he went to John the Baptist to be baptized. Jesus had also been baptized, and, St Luke tells us, "was praying" (3: 21). Jesus speaks with his Father. And we may be certain that he did not only speak for himself but also of us and for us; he also spoke of me, of each one of us and for each one of us. 

And then the Evangelist tells us that above the Lord in prayer, Heaven was opened. 

Jesus entered into contact with the Father, Heaven opened above him. At this moment we can think that Heaven has also opened here, above these children of ours who, through the Sacrament of Baptism, come into contact with Jesus. Heaven opens above us in the Sacrament. The more we live in contact with Jesus in the reality of our Baptism, the more Heaven will open above us. And from Heaven - let us return to the Gospel - that day a voice came which said to Jesus: "You are my beloved Son" (Lk 3: 22). 

In Baptism, the Heavenly Father also repeats these words for each one of these infants. He says: "You are my child". Baptism is adoption and admission into God's family, into communion with the Most Holy Trinity, into communion with the Father, the Son and the Holy Spirit. For this very reason, Baptism should be administered in the Name of the Most Holy Trinity. These words are not merely a formula; they are reality. They mark the moment when your children are reborn as children of God. From being the children of human parents, they also become the children of God in the Son of the living God. 

However, we must now meditate on the words in the Second Reading of this liturgy where St Paul tells us: "He saved us, not because of deeds done by us in righteousness, but in virtue of his own mercy, by the washing of regeneration and renewal in the Holy Spirit" (Ti 3: 5). 

A washing of regeneration: Baptism is not only a word, it is not only something spiritual but also implies matter. All the realities of the earth are involved. Baptism does not only concern the soul. Human spirituality invests the totality of the person, body and soul. God's action in Jesus Christ is an action of universal efficacy. Christ took flesh and this continues in the sacraments in which matter is taken on and becomes part of the divine action. 

We can now ask precisely why water should be the sign of this totality. Water is the element of fertility. Without water there is no life. Thus, in all the great religions water is seen as the symbol of motherhood, of fruitfulness. For the Church Fathers, water became the symbol of the maternal womb of the Church. 

Tertullian, a Church writer of the second and third centuries, said something surprising. He said: "Never is Christ without water". By these words, Tertullian meant that Christ is never without the Church. In Baptism we are adopted by the Heavenly Father, but in this family that he establishes there is also a mother, Mother Church. Man cannot have God as Father, the ancient Christian writers were already saying, unless he has the Church as mother. 

We perceive in a new way that Christianity is not merely an individual, spiritual reality, a simple subjective decision that I take, but something real and concrete, we could also say something material. Adoption as children of God, of the Trinitarian God, is at the same time being accepted into the family of the Church, it is admission as brothers and sisters into the great family of Christians. And only if, as children of God, we are integrated as brothers and sisters into the reality of the Church can we say "Our Father", to our Heavenly Father. This prayer always implies the "we" of God's family. 

Now, however, let us return to the Gospel in which John the Baptist says: "I baptize you with water; but he who is mightier than I is coming... he will baptize you with the Holy Spirit and with fire" (Lk 3: 16). 

We have seen water; but now the question is unavoidable: of what does the fire that St John the Baptist referred to consist? To see this reality of the fire, present in Baptism with water, we must note that John's baptism was a human gesture, an act of penance, a human impulse for God, to ask the forgiveness of sins and the chance to begin a new life. It was only a human desire, a step towards God with their own effort. 

Now this is not enough. The distance would be too great. In Jesus Christ we see that God comes to meet us. In Christian Baptism, instituted by Christ, we do not only act with the desire to be cleansed through the prayer to obtain forgiveness. 

In Baptism God himself acts, Jesus acts through the Holy Spirit. In Christian Baptism the fire of the Holy Spirit is present.

[Pope Benedict, homily 7 January 2007]