Believers Live in God's Love
Jesus makes love the distinguishing mark of his disciples:
A new commandment I give to you, that you love one another; even as I have loved you, that you also love one another. By this all men will know that you are my disciples, if you have love for one another. (Jn 13:34-35)
The measure of following Jesus is love, a love that will manifest itself as unity:
I do not pray for these only, but also for those who believe in me through their word, that they may all be one; even as thou, Father, art in me, and I in thee, that they may be one in us, so that the world may believe that thou hast sent me. The glory which thou hast given me I have given to them, that they may be one even as we are one, I in them thou in me, that they may become perfectly one, so that the world may know that thou hast sent me and hast loved them even as thou hast loved me. (Jn 17:20-23)
Commenting on this passage, the Second Vatican Council proclaimed:
Indeed, the Lord Jesus, when He prayed to the Father, "that all may be one... as we are one" (John 17:21-22) opened up vistas closed to human reason, for He implied a certain likeness between the union of the divine Persons, and the unity of God's sons in truth and charity. This likeness reveals that man, who is the only creature on earth which God willed for itself, cannot fully find himself except through a sincere gift of himself. (Gaudium et Spes, 24)
Unity is essential to the followers of Jesus. It is not just a friendliness or a togetherness, but perfect oneness: ``that they may be one even as we are one''--Jesus' followers are to have the oneness of God!
In other words, Christians should give themselves completely to each other just as do the Persons of the Trinity, who are themselves complete gift of self. By baptism, believers are incorporated into Christ and into each other: For by one Spirit we were all baptized into one body--Jews or Greeks, slaves or free--and all were made to drink of one Spirit. (1 Cor 12:13), and thus they are to reflect the unity of God. This unity transcends all differences among them-- including race, sex, class, politics-- so that there is neither Jew nor Greek, there is neither slave nor free, there is neither male nor female; for you are all one in Christ Jesus (Gal 3:28).
This life of unity within us is built up by our receiving Jesus' body and thus being transformed into his body, as he himself commanded on the night before he died: ``Do this in remembrance of me'' (Lk 22:19).
The cup of blessing which we bless, is it not a participation in the blood of Christ? The bread which we break, is it not a participation in the body of Christ? Because there is one bread, we who are many are one body, for we all partake of the one bread. (1 Cor 10:16-17)
To see past apparent differences among people, we must look with spiritual eyes, not with earthbound eyes of flesh, because it is the spirit that gives life, the flesh is of no avail (Jn 6:63). In the same way we must look with eyes of the spirit at the bread of the Lord's table, trusting completely his words, words that are spirit and life (cf. Jn 6:63):
Jesus said: I am the living bread which came down from heaven; if any one eats of this bread, he will live for ever; and the bread which I shall give for the life of the world is my flesh.... As the living Father sent me, and I live because of the Father, so he who eats me will live because of me. (Jn 6:51,57)
So Jesus' giving of himself to us communicates a share in the life and love of the Trinity and forms the basis of the unity of Christians. To sever this artery of God's life by removing oneself from the table of the Lord is to lose the unity that Jesus prayed his disciples to share. That is why St. Paul attributes the divisions among the Corinthians to the fact that when you meet together, it is not the Lord's supper that you eat (1 Cor 11:20, cf. 1 Cor 11:29).
In the first millennium of the Lord's coming, Christian unity was inviolate. The second millennium saw the schism between the West and the East. In the middle of this millennium, the Protestant Reformation took place. It has only been since the Reformation that Christians have in any numbers neglected the Lord's table. Since that time the number of sects claiming individual autonomy has grown geometrically.
Despite the signs of that Christian unity is not perfect, Christ's holiness preserves the essential unity of his Church. It is not so much having the truth that brings salvation, but striving to know and practice the truth. Jesus guarantees that his followers will persevere in their struggle for the truth, even when their efforts bear no apparent fruit. He merely asks that they work to overcome their own sinfulness in order to become perfectly one, so that they form a seed of unity and life for the whole human race and all of creation.