Well, if you accept Martin as having been the world's foremost expert on cults, why do you call the Catholic Church a cult? Martin never did--- that's why Jack Chick couldn't stand the guy.
Martin Defines cultism in his own terms. If you read the opening chapter of Kingdom of the Cults, you'll find his approach to dealing with the subject. The one failing of his definition is stark in that it fails to include a definition that addresses the Apostacy of Revelation. It fails to address a cult that looks, smells, sounds and breathes so much like Christianity as to be nearly indistinguishable in it's appearance from Christianity and yet follows 'anti-christos' anti meaning In the place of Christ, another Christ, etc. So if the terms all look the same and the names all look the same while having an appearance of "classic theology" as he puts it, they would get a pass on appearance. Catholicism fits this framing.
Catholcism says it believes in Christ; but, it doesn't believe in the Christ of Hebrews that sacrificed once for all time and sat down. Hebrews 9:12 "Neither by the blood of goats and calves, but by his own blood he entered in once into the holy place, having obtained eternal redemption [for us]." ..having obtained for us That is past tense ownership. There is nothing more to obtain. There is nothing more to offer the Father in heaven in purchase of anything - Hebrews says he already owns it. Catholicism doesn't believe or teach that. Hebrews is full of these things that together show us that while having the same terminology, the definitions for the terms differ and the doctrines built around them are opposites. Catholicism believes in a system of grace built upon works. Hebrews rejects this flatly. But rejecting Hebrews, compounds the errors of Catholic understanding of salvation. Catholicism has all the appearances; but, it is quite a different religion apart from Christianity. It is a cult. And I properly label it so because the bottom line for a cult is having an appearance of Christianity while denying Christianity in large part by virtue of irreconcileables.. be it doctrine, terms, pagan practices, etc. Catholicism rejects Biblical salvation and crafts it's own form, following another Christ and another path to heaven that it has defined for itself. That is no small rejection.