This distinction between "parts" of Christ's humanity is very
questionable. When Jesus told his disciples after the resurrection, "I
am with you always", what reason do we have to think that he meant
anything other than that what the words say? Who is Jesus without his
body? (Indeed, a "spiritual body" - cf. my earlier post of this a.m.)
Sure, we don't see Jesus as people did circa 30 A.D. How is he
with us in the body? Part of the answer is the Sacrament: "This is my
body." I realize that many protestants don't think that really means
"this is my body", but there is no good reason for such an objection.
Of course there are many questions here about the relation between
Christ's presence in the Lord's Supper and his resurrection, how we
relate all this to scientific understandings of the world, etc. But we
would do best to start with the catholic (note small c!) belief that
Christ is fully present in the Sacrament and proceed from there to try
to answer questions.
I'm sorry I won't be around for the next week to field comments
which this is likely to generate. So it goes.