The definition of delusion is: a false belief that is based on an incorrect interpretation of reality (Harvard Health Publishing, Harvard Medical School).
Or, alternately from Merriam-Webster: Delusion - a persistent false psychotic
belief regarding the self or persons or objects outside the self that
is maintained despite indisputable evidence to the contrary.
It's what the word means. If you don't like it, then take it up with Harvard Medical School and Merriam-Webster.
Next, you confuse religious beliefs with ethnicity and culture. They're different even if the same word is used to refer to both in some cases. I know many Jewish people who are atheists, but love their culture.
Finally, I am a scientist. I teach biology, chemistry, physics and psychology at the secondary level.
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