Perhaps this is connected to the question you make:

Cyb somewhat beat me to it, but...

Most likely that wouldn't happen if Religion as a word didn't have the negative connotations it generally has. And I'm guessing a lot of users who approach psychedelics in a thoughtful way, or as an expression of a deep need, have their issues with dominant religions and reject certain dogmas, or at least question them.

In a context where "religion" would be as emotionally neutral a word as it is in dictionaries, using the word would be easier.  When religion does not make people automatically think of worshipping and followers, seeing people who believe because of their deep personal insights should be easy. I don't think that's the norm in the major religions in our society.