14 Here we need to consider yet another aspect: this sacramental “mysticism” is social in character, for in sacramental communion I become one with the Lord, like all the other communicants. As Saint Paul says, “Because there is one bread, we who are many are one body, for we all partake of the one bread” ( 1 Cor 10:17). Union with Christ is also union with all those to whom he gives himself. I cannot possess Christ just for myself; I can belong to him only in union with all those who have become, or who will become, his own. Communion draws me out of myself towards him, and thus also towards unity with all Christians. We become “one body”, completely joined in a single existence. Love of God and love of neighbour are now truly united: God incarnate draws us all to himself. We can thus understand how agape also became a term for the Eucharist: there God's own agape comes to us bodily, in order to continue his work in us and through us. Only by keeping in mind this Christological and sacramental basis can we correctly understand Jesus' teaching on love. The transition which he makes from the Law and the Prophets to the twofold commandment of love of God and of neighbour, and his grounding the whole life of faith on this central precept, is not simply a matter of morality—something that could exist apart from and alongside faith in Christ and its sacramental re-actualization. Faith, worship and ethos are interwoven as a single reality which takes shape in our encounter with God's agape . Here the usual contraposition between worship and ethics simply falls apart. “Worship” itself, Eucharistic communion, includes the reality both of being loved and of loving others in turn. A Eucharist which does not pass over into the concrete practice of love is intrinsically fragmented. Conversely, as we shall have to consider in greater detail below, the “commandment” of love is only possible because it is more than a requirement. Love can be “commanded” because it has first been given.
Source: Deus Caritas Est (Vatican.va)