I'm 32 years old, and didn't really pick up the whole message board / forum thing until I was 28 or so. It is my understanding that "Trolling" is posting something you know will generate negative feedback, for the purpose of then [figuratively] bashing those people over the head with reasons that they are "wrong". You already have an opinion, and want to force it on other people. The post isn't made with the intent to "discuss", the intent is to angrily preach, for lack of a better term.
For example, let's say I'm Pro-choice, and decide to post about the good things that pro-choice policy leads to. If I'm doing that to inform, and am able to stick to professional, fact based arguments, then that isn't trolling, despite the probability that people are going to get hot under the collar. If my intention is to lure people into presenting arguments that I feel I can crush using whatever means are at my disposal, particularly ridiculing different belief systems, then that's trolling.
I suppose in the end, only the poster knows their intentions, and even then, some people aren't all that self-reflective to realize the nature of what they're doing. Posting to be provocative is one thing. Posting to begin a genuinely discussable topic isn't trolling, even if it's hotly contended.
Posting for the purpose of belittling someone else, even in a structured and controlled manner, is Trolling. Assuming that isn't the case, things are probably good.
NOTE: This isn't to say that this will typically be in good taste, or appropriate, only that I feel a poster's intention is the primary determining factor in a case of Trolling accusations. I think the term Trolling has become a buzzword that people use to describe any type of unwelcome debate / argument / provocative statement / anything they don't agree with. Anyone that disagrees with me is a Troll.