In a nutshell, they claim that the Apostolic succession of the Catholic Church was broken, therefore breaking the authority of the Catholic Church. The year of the break varies by the protestant faith in question and of course is totally and easily debunked.
Also by one of my favorites, Patrick Madrid at EWTN:
This goes through the Mormon side; however, one of the positions the Mormon Church holds at the core is that the Catholic Church is in a state of apostasy: ewtn.com/library/ANSWERS/mormon2.htm
In some Christian churches they teach about a “great apostasy” where Christianity got put in the hands of pagans. A common refrain, “Rome didn’t convert to Christianity, Christianity converted to Rome,” sums up the thinking. Thus, an apostate church would be a false church involved in said supposed “apostasy.” They believe that this “apostate church” suppressed and killed the “real Christians.” I have been a member of 3 different churches which taught something along those lines, but it is nonsense. I do understand why they believe it, but they’re wrong.
Apostate means to stand off from, hence a defection or deserter.
Now, what is funny, if those people who say that the Catholic Church is apostate are Protestants of some kind, they need to be reminded that Protestants are derived from the Catholic Church. Protestants inherited their belief in God and in Scripture from the Catholic Church. They are therefore derived from an apostate church! They themselves are apostates once removed!
If these people are Mormons or Jehovah’s Witnesses, or Church of Christ, etc, these groups themselves are derived from Protestantism or are apostate from Protestantism and hence are apostates twice removed!
What I want to know, is how a true church can be derived from a false church? But that is what some people seem to think. It makes you wonder.
The definition of apostate is one who renounces a formerly held belief. So the question you can pose (once the blood pressure med kicks in) to those on the other forum, is which belief did the Catholic Church hold formerly that it now renounces. Technically that’s what’s being said by applying the apostate label.
The Mormon Church (i.e., The Church of Jesus Christ of Latter-day Saints) did not break away from any other denomination so it’s neither Protestant nor once, twice, or thrice removed from any other denomination.