What is the Lutheran response to the argument made by some, that Christ couldn't have meant "this is my body" in a literal sense, since he was himself bodily present in the midst of the disciples, in the same upper room, as distinct from the elements?
I believe Martin Luther would have just said that it was a divine mystery, and something that we as mere mortals are not supposed to be able to completely comprehend:
I do not ask how Christ can be God and man, and how his natures could be united. For God is able to act far beyond our imagination. To the Word of God one must yield. It is up to you to prove that the body of Christ is not there when Christ himself says, ‘This is my body.’ I do not want to hear what reason says. I completely reject carnal or geometrical arguments, as for example, that a large body could not fill a small space. God is above and beyond all mathematics, and his words are to be adored and observed with awe. God, however, commands: ‘Take, eat; this is my body’. I request, therefore, a valid proof from Holy Writ that these words do not mean what they say. (Marburg Colloquy, 1529)
For Luther, Faith goes beyond reason.