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Muslims are obviously not delusional. The farthest I would go to say is that some allow their prejudices to override their intellect --- > to a greater extent than the average person does (because we all do it, LR).
A person who believes in Zeus or Ra is basing his belief on a far less impressive body of evidence than somebody who believes in Mohammad.
You can differentiate between Felix' record and Ken Cloude's. Why can't you differentiate between Mohammad's and Ra's?
Einstein didn't believe in Ra, because he wasn't delusional. He did, however, believe that a transcendent Mind was behind the laws of physics. The difference was in the levels of evidence.