Steve,
No need to be forgiven for simplicity because you have expressed an understanding of an amazing property of infinity when you showed that you can subtract from infinity but you cannot diminish it. Isn’t that somewhat like our relationship with God; before there was a universe there was the infinite God from which we emerged without diminishing Him one iota? I think it is. There are those that participate in this forum that are not aware of that property of infinity. However, you may want to reconsider the (x-x) = x. Georg Cantor, the originator of transfinite algebra, identified an infinite string of infinities that he labeled: aleph(0), aleph(1), …aleph

…aleph(infinite), so when you say infinity - infinity = infinity, you are absolutely correct if you mean: aleph (1) - aleph(0), but I am not sure that it is correct to say that: aleph(0) - aleph(0) = aleph(0).
Anyway that leads me to a question concerning what you conclude from the impossibility of diminishing infinity. Am I missing something that I can’t grasp in between “…and get the same answer” and “…the universe cannot be infinite”? I agree wholeheartedly with the conclusion, but cannot rationalize getting there from the premise. Can you illuminate further? Even if you can’t I think rather than dropping the intelligence factor of this thread you have raised it because if we can find an argument that links a beginning of the universe and the Creator to the mathematical concept of infinity then we have accomplished at the very least a answer to the subject of this thread: Can God be proven mathematically?
Yppop