the difference is that governments don't encourage people to believe the Men In Black are coming for them, and the aliens don't have representatives here on Earth so far as I am aware. Those delusions are *entirely* delusions. Whereas the Church does encourage people to believe in hallucinations, signs and portents, God speaking to his chosen ones in a voice that only they can hear, the Angels coming down and impregnating a woman, the Angels telling a man to sacrifice his son and the man being rewarded for being about to go through with it... They present these things as entirely POSSIBLE, entirely REAL, entirely RIGHT and due to happen again any time soon. The Church actively encourages these beliefs, they have a large and influential power structure and a history going back decades, they have history books full of people who died for the beliefs, and the support of thousands, millions of people worldwide. Suddenly our schizophrenic isn't an isolated nut believing in things that no-one else thinks can be true - he's part of a HUGE community who will all back up his beliefs. Mentally vulnerable people are therefore inclined to, when they hear a voice that says it's the Voice of God, really really believe they are one of the Chosen Ones, the next prophet, the Son of God, cry out "it's happening just like the Bible said it would and it's happening to ME!!" and off we go. Aliens would be easier to deal with. Religion is not to blame for their condition, but it must take responsibility for encouraging people with delusional disorders to blur their line between what is a delusion, a symptom of the illness, and what is a real possibility.