I think the problem here is that the Roman Catholic Organization doesn’t say that “Mary is a temple of the Holy Ghost, as is all Christians”. The RCO refers to Mary as “Temple of the Holy Ghost”.
The “T” in “Temple” is capitalized. This denotes the same thing it does in the following sentence:
I follow the Truth.
The “T” in the word truth is capitalized to denote that it is referring to God. The capitalization also makes it a title. This, of course, is a title that can only apply to “a god”. So “Temple of the Holy Ghost” is in the same way a title with a capital letter that gives the appearance of referring to “a god”.
Jesus once stated “Tear down this Temple and in three days I’ll put it back together.” See how the word Temple is capitalized?
What the RCO does is it commandeers terms of Christianity and applies them to pagan things. You can see it in the way the RCO has commandeered the word “catholic”.