It’s not just that he was mentally ill. He was encouraged by our new society that told him nothing was his fault. He also needed to watch a few of the gay guys tied to chairs getting thrown off the roof videos out there. If it sank in it may have lessened his support for islamic terrorism.
No, he was probably a Muslim himself or at least a sympathizer.
He was definitely crazy, but crazy people - especially with paranoid disorders, which he clearly had - often latch onto some violent ideology, movement, etc. because it makes them feel sane and justified.
This is even more the case when it’s an ideology that is itself insane and based on paranoia and violence, i.e., Islam.
But it also happened during the French Revolution - the mentally ill streamed into the streets and were completely identified with the cause and were considered sane by all of their “co-religionists” because the whole ideology was paranoid and violent.
Our current mixture of black racist, Islamic-tinged paranoid violent ideology, seemingly endorsed by the White House, is a magnet for crazy people.