Of course, we receive Holy Communion into our mouths, but first it enters the soul and that is where our joining with Christ takes place like the Apostle Paul says: "But he that is joined to the Lord is one spirit with Him" (1 Cor. 6:17). Without joining with Christ, man is of his own the old man who has nothing in common with God. What does Christ ask of us in order to sanctify us through the Holy Mysteries? It is the cleansing of the soul, faith and love of god, ardent desire and longing for Holy Communion. These draw sanctification close, and that is how we should commune, because many are those who come to the mysteries and not only do they not benefit, but actually return with greater sins. - St. Nicholas Cavasilas - Interpretation of the Divine Liturgy