What is wrong with theistic beliefs?

[Angrboda]

We're all laboring under at least a few illusory beliefs or concepts.  If that were the reason that theism were problematic than we could see those same problems in all other examples of illusory beliefs or concepts - but we don't. While the belief in such a god is nothing more or less than the affirmation of the illusory.....it's the fact that this particular illusion is an echo chamber for all of our basest compulsions that makes it problematic.

I think the centrality of the delusion is a factor as well, which isn't under the majority of harmless delusions. Believing it's the most important thing in your life and that it comes from God himself has effects that more mundane beliefs lack.

Who in heck is Gae Bolga?