"That they may be one just as we are"
When Christ became as we are, that is to say when he became man, even though he was God by nature the Spirit anointed and consecrated him... He himself sanctified his own body and the whole of creation became worthy of sanctification. The mystery effected in Christ is the rule and way towards our own participation in the Spirit.
So that we, too, might be made one and dissolved in union with God and each other, divided though we may be by our different individualities, souls and bodies, the Son of God designed and prepared a means of bringing us together thanks to the wisdom that is his and in accordance with his Father's plan. Through one single body, his own, he bestowed blessing on those who believe in him and made of them one body with him and amongst themselves in a mystical communion.
Who, then, could divide or deprive of their physical union those who, through this sacred body and it alone, are united in the unity of Christ? If we share the one bread then we make a single body (1Cor 10:17). For Christ cannot be divided. And so the Church is also called the body of Christ and we are its members according to Saint Paul's teaching (Eph 5:30). All of us united to the one Christ by his sacred body; we receive him, unique and undivided, into our own bodies. We are to think of our own bodies as belonging to ourselves no more.