"God is Love, and he who abides in Love abides in God, and God abides in him" (1 Jn 4:16). These words from the First Letter of John express with remarkable clarity the heart of the Christian faith: the Christian image of God and the resulting image of mankind and its destiny. In the same verse, Saint John also offers a kind of summary of the Christian life: "We have come to know and to believe in the Love God has for us." We have come to believe in God's love: in these words the Christian can express the fundamental decision of his life. Being Christian is not the result of an ethical choice or a lofty idea, but the encounter with an event, a person, which gives life a new horizon and a decisive direction. Saint John's Gospel describes that event in these words: "God so loved the world  that he gave his only Son, that whoever believes in him should... have eternal life" (3:16). In acknowledging the centrality of Love, Christian faith has retained the core of Israel's faith, while at the same time giving it new depth and breadth. The pious Jew prayed daily the words of the book of Deuteronomy which expressed the heart of his existence: "Hear, O Israel; 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" (6:4-5).