If you've ever taught or attended Bible studies or other adult Christian education, you know that some people have a tendency to think themselves quite the intellectuals for coming up with pesky heretical questions--e.g. "What if 'angels' are really people? What if you're an angel and you don't know it?"
Sometimes I have found myself in the position of being an irritated classmate to such persons, sometimes I am the eager-to-explain-it-all teacher, and other times, I am that heretic, or I could be. But usually, when I have such ideas, I tend to keep them to myself, because I've learned by now that most heresies, while they may seem very clever at first, turn out upon closer investigation to be quite silly, poorly thought out, and easy but tedious to refute.
For example: I have participated in many, many a discussion about the classic formulation of the doctrine of the trinity. And I know the standard heresies. But I've always wondered, "How do we know there are only three persons in the trinity? What if there was a little known fourth person--kind of like the often-forgotten fourth Beatle? Or, since God is infinite, what if there were an infinite number of persons in the trinity--er--the 'infinity'? How can we say we know God exists only in three persons? At an earlier stage in revelation history, it was 'known' that God was one--no trinity at all--so what if someday we find out there are even more divine persons?"
Seems like a reasonable question, right? But when you start thinking about it, it's actually not that interesting or helpful. Because while it is of course possible that there could be more persons in the trinity than we know about, it's pretty much irrelevant because if they exist, they haven't been revealed to us. And the idea that deities from other religious traditions might be additional divine persons equal to the three in the trinity is, I think, ultimately a dead end, since it requires a highly artificial mixing of worldviews (that is, when Hindus, for example, talk about their pantheon, they are talking about a significantly different concept of the revelation/manifestation of God than the Christian concepts involved in explaining the doctrine of the trinity).
Furthermore, it is integral to the Christian belief system that Jesus uniquely reveals the fulness of God's glory, and that the church has preserved a faithful witness to the Christ-revelation in scripture, and that witness contains only indications of three persons in the trinity, not more.
So, anyway ... I find that heresies turn out not to be so interesting after all, and orthodoxy is really the more fascinating and compelling avenue for thought and discussion, because it contains within it so many surprising, beautiful, mysterious paradoxes. Like the classic doctrine of the trinity.