The Presence of Christ in the Lord's Supper
"Where two or three are gathered in my name, there am I among them."
Classic, orthodox Christology as defined by the Council of Chalcedon in AD 451 holds that in the one person of Christ are perfectly united a human nature and a divine nature. In this union, the two natures are joined without mixture, confusion, separation, or division, each nature retaining its own attributes. The divine nature does not become semi-human and the human nature does not become semi-divine. Christ is truly God and truly man, not a divine-human hybrid who is neither truly human nor truly God.
Since each nature retains its own properties, Christ's human nature possesses all of the non-sinful limitations that are de nitional of humanity. This is evident in the Gospels, which tell us, for example, that Christ experienced human limitations such as hunger (Mark 11:12). But even in His glorified state, the human nature of Christ is still limited in ways that are not a consequence of the fall. His physical body, one of the aspects of His human nature, is localized in heaven. It can be no more omnipresent than our human bodies can be. We see evidence for the localization of Christ's body in heaven in passages such as 1 Thessalonians 4:16, which speaks of Christ in His humanity descending from heaven.
However, because Christ has a divine nature as well, He also possesses divine attributes. The person of Christ is omnipresent on account of His divine nature. His human nature remains localized in heaven, but because Christ is also truly God, He is omnipresent and ever with us due to His divine nature. And, because God is spirit (John 4:24), the nature of Christ's omnipresence is spiritual. Thus, we affirm that Christ is truly and spiritually present in the Lord's Supper.
Yet when we commune with Christ at His table in the supper, we are not communing with His divine nature alone. We are communing with a person, and to commune with the divine person of the Son of God, because He has a truly human and truly divine nature, means that we are communing with the God-man. His human body and soul remain in heaven, but we have access to the whole Christ because we are communing in the supper with the divine person in whom both omnipresent deity and localized humanity are united. By faith, as Westminster Confession 29.7 states, we feed on Christ spiritually, and both His humanity and His deity nourish us. His presence is spiritual, but via that spiritual presence, we commune with Jesus in all His humanity and deity.
Coram Deo
When we come to the Lord's Table, the human nature of Christ is not in the room with us but is in heaven. However, because Christ is spiritually present, we nevertheless also commune with His humanity. We are lifted up to heaven, as it were, to fellowship with the whole Christ. That is why the Lord's Supper is such a solemn and joyous occasion.