The difference is that while the nutty brother may think God is telling him to do something, there is nothing in Christianity that supports this. Islam, on the other hand, is full of “orders from Allah” to kill or destroy the infidels.
Islam is basically a sort of institutionalized form of psychosis, founded on the hallucinations of a nutty 7th century Arab, and people who fall into its sphere, particularly if they are already somewhat unstable, will be easily swept into the psychotic group project of Islam.
That first paragraph is spot on, and it is something that Leftists refuse to see or admit. The denial of reality is incredible.