Dear Brothers and Sisters,

1. In ancient Israel the fundamental commandment to love God was part of daily prayer: "The Lord our God is one Lord; and you shall love the Lord your God with all your heart, and with all your soul, and with all your might. And these words which I command you this day shall be upon your heart; and you shall teach them diligently to your children, and shall talk of them when you sit in your house, and when you walk by the way, and when you lie down, and when you rise" (Dt 6: 4-7).

The basis of this requirement to love God totally is the love that God himself has for man. He waits for a true response of love from the people he loves with the fondest love. He is a jealous God (cf. Ex 20: 5), who cannot tolerate the idolatry which constantly tempts his people. "You shall have no other gods before me" (ibid., v. 3).

Israel gradually understood that, in addition to this relationship of profound respect and exclusive worship, its attitude to the Lord had to be filial or even nuptial. The Song of Songs should be understood and interpreted in this sense, transfiguring the beauty of human love into the spousal dialogue between God and his people.

The Book of Deuteronomy recalls two essential characteristics of this love. The first is that man would never be capable of it, if God did not give him strength through "circumcision of the heart" (cf. Dt 30: 6), which frees it from every attachment to sin. The other is that this love, far from being reduced to sentiment, is concretely expressed by "walking in the ways" of God and by keeping "his commandments and his statutes and his ordinances" (ibid., v. 16). This is the condition for "life and good", while turning the heart to other gods leads to "death and evil" (ibid., v. 15).

2. The commandment in Deuteronomy remains unchanged in the teaching of Jesus, who describes it as "the great and first commandment", closely relating it to love of neighbour (cf. Mt 22: 34-40). By expressing this commandment in the same terms as the Old Testament, Jesus shows that on this point Revelation had already reached its apex.

At the same time, the meaning of this commandment achieves its fullness precisely in Jesus' own person. In fact, it is in him that man's love for God reaches its greatest intensity. From now on, loving God with all our heart, with all our mind and with all our strength means loving that God who revealed himself in Christ and loving him by sharing in the very love of Christ "poured into our hearts through the Holy Spirit who has been given to us" (Rom 5: 5).

3. Charity is the essence of the new "commandment" that Jesus taught. In fact, it is the soul of all the commandments, whose observance is further confirmed and indeed becomes a clear proof of one's love for God: "For this is the love of God, that we keep his commandments" (1 Jn 5: 3). This love, which is also love for Jesus, is the condition for being loved by the Father: "He who has my commandments and keeps them, he it is who loves me; and he who loves me will be loved by my Father, and I will love him and manifest myself to him" (Jn 14: 21).

Love for God, made possible by the gift of the Spirit, is therefore based on the mediation of Jesus, as he himself says in his priestly prayer: "I made known to them your name, and I will make it known, that the love with which you have loved me may be in them, and I in them" (Jn 17: 26).

This mediation becomes concrete especially in the gift he made of his life, a gift which, on the one hand, testifies to the greatest love and, on the other, demands the observance of what Jesus commands: "Greater love has no man than this, that a man lay down his life for his friends. You are my friends if you do what I command you" (Jn 15: 13-14).

Christian charity draws from this source of love, which is Jesus, the Son of God offered for us. The ability to love as God loves is offered to every Christian as a fruit of the paschal mystery of his Death and Resurrection.

4. The Church has expressed this sublime reality by teaching that charity is a theological virtue, which means a virtue that refers directly to God and enables human creatures to enter the circuit of Trinitarian love. Indeed, God the Father loves us as he loves Christ, seeing his image in us. This image is painted in us, so to speak, by the Spirit, who, like an "iconographer", accomplishes it over time.

Again, it is the Holy Spirit who draws the basic traits of the Christian response in our inmost depths. The dynamism of love for God thus flows from a sort of "connaturality" brought about by the Holy Spirit who "divinizes" us, in the language of the Eastern tradition.

Through the power of the Holy Spirit, charity shapes the moral activity of the Christian; it directs and strengthens all the other virtues, which build up the new man within us. As the Catechism of the Catholic Church says: "The practice of all the virtues is animated and inspired by charity, which "binds everything together in perfect harmony' (Col 3: 14); it is the form of the virtues; it articulates and orders them among themselves; it is the source and the goal of their Christian practice. Charity upholds and purifies our human ability to love, and raises it to the supernatural perfection of divine love" (n. 1827). As Christians, we are always called to love.