[All-American]

Why not just go with what the word means? An anti-Mormon is one who opposes and/or fights against Mormonism.

If one insists upon qualifiers, I'd say that such opposition ought to be active and deliberate. For example, my Elder's quorum president will undermine more testimonies in a month than SU could possibly do in a lifetime, but because the damage he does to the church is a result of his dim-witted stupidity in spite of his good intentions, I wouldn't classify him as an Anti.

I doubt there's ever been a really good "anti." It may be that the church is going to be essentially unopposed from without. Even the most effective "antis" are the ones that were once members, but then left-- but then again, even those worth mentioning haven't really done that much. (I wonder if the net result of Fawn Brodie's works, for example, actually brought MORE people to the church by encouraging a reactionary movement amongst the LDS "intellects." It'd be an interesting study.)