Religious moderates can truly help against fundamentalism by undercutting the epistemic basis of fundamentalism. Stop attaching the words "truth", "knowledge" and "reality" to what are fundamentally opinions, and which religious moderates actually treat as opinions in the moral sense, i.e. without a moral duty to believe.
As much as we all dislike fundamentalism, it's not enough to be against fundamentalism only because we don't like it. We need to take a principled stance against fundamentalism. Fundamentalists believe their beliefs to be true, and and they promote their beliefs precisely because they take that truth-belief seriously in the moral sense as entailing a duty to believe. We can undercut them only by excluding religious belief from the realm of truth.
It's a simple request, but I understand it's hardly easy. Never having been religious, I simply cannot evaluate how difficult it would be to retain the positive aspects of one's religious while abandoning the belief in its truth. But if religious moderates honestly want to help, I cannot see an alternative.
This is about it for this morning; I apologize to those awaiting a response, but it'll have to wait until this afternoon or tomorrow morning.