Exactly. I mentioned it more for the benefit of those who often say something along the lines of "you just don't listen to the Spirit." That is why we need to know our doctrine. It's also why we need to understand the context of scripture, as I mentioned earlier.I'm not sure exactly what you mean by that, but there are those who have received confirmation disagreeing with the one you say you have received.
Mormons, whom you've referred to some, say that you'll know their teachings are true, when you get a "burning in the bosom". As you've stated, it is obvious, because Scripture makes it so and for no other reason, they've been deceived.
The Creeds, BTW, came out of the fire of controversy to preserve the teachings of the bible itself. The Arians I mentioned could "affirm" everything the bible said, they just meant something else than the plain intent of the writers when they said it. This lead to a heresy which made Christianity unintelligable as a system. So the Credal writers expressed the Apostolic faith (written in the bible) in absurdly explicit (as an aquaintance of mine liked to say) terms in the Creeds.
They are more useful than many modern Christians think, as one can take almost anything from the bible if they try to read it in a vacuum. And this was not what the reformers meant when they demanded on the authority of Sola Scriptura either. Calvin had an impressive grasp on the fathers. He just did not elevate them to an equal authority with the scriptures.
The teachings of Copeland's I remember being especially struck by the similarity to Mormon thought was on the deification of man (this was a long time ago so bear with me). It was something about adam being endowed with god-like powers before the fall, and that man can become a god in his own right.
I am usually charitable when hearing odd positions, I tend to think 'well maybe they meant it this way or that way' (you know like Athanasius-my hero as you all probably know by now-would have meant it) which is not unorthodox. However it sticks out in my memory because Copeland actually took the time to say that the Orthodox position of glorification was wrong, and he had the correct one. No equivocating at least. There were other remarks and so one that kind of cemented that thought for me.
these are not central, and I believe God did not give clear mandates about many things to give us some wiggle room-or we wouldn't have anything to debate, and that would be sad.Other things... divine healing, glossolalia, modern-day prophecy... to me those are more peripheral issues. If you have Salvation straight, you can be wrong on that other stuff and still make it in.

Didn't we already argue against the Universalist position a few times recently? I seem to remember that was a real head-meet-brick-wall-ish one.