Traditionally when I hear arguments for maintaining the doctrine of Christ’s real presence in the Lord’s Supper, the foundational argument is based on the promise, the direct testimony of Christ that “this IS my body”, “this IS my blood.” In effect, to say that Christ is not present bodily in, with, and under the bread and the wine is to call Christ a liar. The little word “is” wins the day, because if Christ had wanted to say “symbolized” or “represents” he could have done so. Instead, Christ distributes the bread and the wine to his disciples and says, “This is my body, given for you.” He then goes on to say, “This do in remembrance of me.” Another inescapable commission, that we are to do what he does, that is, to distribute bread and wine while saying and believing it is truly his body and blood. All because of the testimony of Christ.
Interestingly, Melanchthon in the Apology takes a slightly different tack. First, he argues from tradition. The Roman church as well as the Greek church have always maintained the same position, namely, the bodily presence of Christ in the the Supper. But then he continues the argument in a way that is profound and challenging. He admits, of course, that we have a close spiritual connection to Christ by true faith and sincere love (who’s, his or ours, is not mentioned). But he goes on to indicate the importance of the bodily presence because we are all one body in Christ because we partake of the one bread. Or later, citing approvingly Cyril of Alexandria, “Since this is in us, does it not also, by the communication of Christ’s flesh, cause Christ to dwell in us bodily?”
So the truth of the real presence is not just one of words and promises, which themselves are bodily and mighty and essential to our faith, but also because in our reception of Christ’s body, we participate in his body, that is, the body of Christ, which is not a spiritual body but a resurrected and living body. That is to say, our confession of the real presence of Christ in the Supper is connected to our confession that Christ came “in the flesh”, that Christ truly had a body, and if we are members of that body, we are partakers not just of a spiritual unity, but of an actual body. The doctrine of the real presence of Christ is connected in a profound way with our belief that Christ came in human form, that Christ is the body over which death has no dominion.