I just read the guy's "manifesto".
He is not insane. But he is a monster who worships the deity of race and is ready to kill others as an offering to it. It would be better if he were insane; but rather, he is one fruit among many of those who spend their time online looking at memes that dehumanize others, and then going outside and interpreting reality through these.
I am annoyed by the couple of Christian justifications he mentions (although he himself is not Christian), but it would probably be against the staff post to say what they are and what my response is.