I too do not find the reference to theodicy entirely transparent, but here's my interpretation, at least. The origin of the idea of genius is supposed to be a

I too do not find the reference to theodicy entirely transparent, but here's my interpretation, at least. The origin of the idea of genius is supposed to be a means of filling in a gap left by the loss of cultural belief in God and angels and so forth; that provides the theological connection. So, it seems to me it's saying that the belief in genius justifies the existence of evil because our genius-'gods' are in fact still basically human. Specifically calling it "theodicy of the human mind" feels like it's suggesting something more, but, to quote the article a bit more, it's not the traditional theodicy that tries to justify the ways of god to suffering humanity, but rather one that permits us to see ourselves, in however attenuated a sense, as the point of it all. So, yeah. Genius == theodicy because "God is really just us" or something like that. It's a pretty big stretch from the normal meaning of the word, but that's the best I can make of it.