The Problem of the Ascension

Here is an argument that seems to pose a prima facie problem for the core Christian doctrine that Christ ascended into heaven:

(1) Christ has a body
(2) Whatever has a body is physical/extended
(C1) Therefore Christ is physical/extended [1,2]
(3) Christ ascended into heaven
(4) Whatever ascends into heaven is in heaven
(C2) Therefore Christ is in heaven [3,4]
(5) Heaven is non-physical/unextended
(6) If something is non-physical/unextended then whatever is in it is non-physical/unextended
(C3) Therefore Whatever is in heaven is non-physical/unextended [5,6]
(C4) Therefore Christ is non-physical/unextended [C2,5]
(C5) Therefore Christ is physical and not physical/ extended and not extended. [C1,C4]

Holding onto (1) seems to be essential to the Christian message given the theological thesis that whenever a human soul does not poses a body, the human is dead and the fact that Christ is not dead (“Christ is risen indeed!”).

One may also argue for (1) on medical grounds. Whenever a humans brain and heart cease to function, the human is dead, and if Christ has no body then he has no brain and no heart, so he would have no brain and heart to function, so he would be dead, but as I said before Christ is not dead, therefore Christ must have a body. (It would seem odd to think the one that defeated death ascended into heaven only to be dead again).

One may also argue for (1) on the basis that it follows from the traditional view of the Eucharist. Whether one accepts consubstantiation or transubstantiation one must believe that the ascended Christ has a body for both views entail that he does.

(2) just seems to be an essential truth about what bodies are; they are extended, physical things. It seems impossible to imagine something being a body but not being extended. What would it even be to be an unextended body? It seems that any unextended thing would not be a body at all.

(3) is just the Christian doctrine in question. Denying it would result in either denying Christianity full stop or falling into some extreme heresy such as docetism.

(4) just seems to be a truism. If I ascend into space then I am in space, likewise if I ascend into heaven I am in heaven.

(5) Seems to follow from the standard Christian belief that heaven is a spiritual realm. If it is spiritual it is not bodily. If it is not bodily then it is not extended. Further if it is spiritual, since spirits are unextended then it is unextended.

(6) Seems to me to be true for how could an extended thing be in an unextended place?

So the question is what premise(s) could one push on to get rid of the problem in a non-ad hoc and convincing way or is there a way to render the argument invalid?

I haven’t seen much work at all on this problem. William Lane Craig has a small reply to an argument a long these lines, he seems to think that we ought to deny (1). I find this completely unsatisfactory for the reasons I gave above and I believe that it is probably unbiblical. So let me know your thoughts because I have been thinking about this a lot recently and find it to be a very interesting problem.