Was listed at RFV with the comment, “Needs attestation of use as true adjective. See Wiktionary:English adjectives.” However, AFAIK there's no policy requiring such attestation. In general it's good to apply this sort of test, but I think this might be an exception.
The issue is simply that Christofascist is rare — b.g.c. gives less than twenty hits — and the majority of the b.g.c. hits are formally ambiguous between noun and adjective readings. (In some cases the noun readings are a bit, um, implausible — "christofascist people" clearly doesn't mean "people of christofascists", and a "philosopher kings"–type reading seems far-fetched — but Wiktionary:English adjectives makes no concessions on that point.) A few hits are predicative and therefore clearly adjectival, but these are secondhand — things like “those right-wing Christologies to which Dorothee Soelle has referred as ‘Christofascist’” (mention) and “Some of the pluralists speak derisively of the high Christology of trinitarian dogma as christofascist and […] ” (arguably use, but basically mention IMHO), “It would be unfair to apply the term “Christofascist” to this approach, […] ” (mention, and also hard to definitively prove as adjectival, though IMHO an attributive noun couldn't be mentioned this way).
I say keep: there are plenty of reasons to think this is an adjective, and no reasons SFAICT to think that it isn't.