What is a cult?So that is it? Any deviation from the bible at all and you are a cult. Most protestant churches would actually admit to being a cult under that definition. That is they don't claim to have the true biblical faith without any errors. Some claim to be 100% right on matters of salvation but this definition does not even limit it to that. Any deviation at all from the correct biblical interpretation and you are a cult.
A cult is any group which teaches doctrines or beliefs that deviate from the biblical message of the Christian faith.
The problem is that limiting it to matters of salvation would matters of salvation would make people ask, "What are the true doctrines of salvation?" Protestant churches disagree even on that. So defining a cult that way really does not work. So the BGEA list a few examples.
Some of these groups are Jehovah's Witnesess, Mormons, the Unification Church, Unitarians, Spritualists, Scientologists, and others,The obvious problem is the use of the word "others." How do I know if the group I want to join is one of the "others?" They just don't have an answer because they know Christians will disagree wildly on what should be considered a cult.
Now they have drawn attention to this whole thing by removing Mormons from the list of cults. Why did they do that? Politics. Saying Mormons are a cult group makes Romney seem less reasonable as a candidate for president. But should politics influence how Christians answer a question like this?
It goes back to the classic Called To Communion article on Sola Scriptura and Solo Scriptura. What it says is that you can't really distinguish in a consistent way between reasonable opinions on biblical interpretation and unreasonable ones. That at the end of the day all bible-only Christians do exactly the same thing as cult leaders do. They do it to a lesser degree but the principle they follow is exactly the same.
What that says is that Sola Scriptura makes it impossible to define a cult as long as they claim to follow the bible. You can only say they are wrong in your opinion. That is that you disagree with them more strongly than you disagree with some other churches. The point is that your opinion is the central reference point. So they are cult-like relative to your theology but not in an absolute sense.
To get an absolute definition you need to look at Christian tradition. How far is a group from the historical center of Christianity? But even then you would need to define that in an objective way. You end up with something very similar to the Catholic notion of sacred tradition. That leads to the realization that Catholicism is closer to the center of Christianity then the particular brand of protestantism I follow. You can see why most protestants don't want to go there.