It's not a possibility. Anybody who has studied mythology will tell you ALL religion - including his or her own - is, by definition, mythology.

"Myth" has two definitions, and because they are opposites, it confuses people very often.

Joseph Campbell uses the definition of "a story - literally true or not - told to reveal higher metaphorical and spiritual truths." From this perspective, not only is all religion mythology, but also a large number of jokes and even some biographies of living people. This is the one closely related to the original Greek word "mythus," which just means anything conveyed through speech.

Adam Savage and Jamie Hyneman use the more common usage definition (which only started in the mid-19th century) of "a claim or belief that is false."