Sci-Fi Religions Vs. Fantasy Religions

After watching an interview with an Israeli scientologist, where the interviewer mocked the idea of aliens coming to Earth 75 million years ago, I came to the conclusion there isn't really much difference between the mainstream religions and UFO religions. Of course the idea of aliens creating humanity is ridiculous, but are the mainstream creation myths any more believable?

The main difference between the more accepted religions and religions like Scientology is the literary genre of their origin stories. The myths of the bible, ancient European mythologies and Eastern religions all use the magic of fantasy fiction. Pillars of fire, virgin births, monsters and rain dances can easily be placed in the same section of the library as Harry Potter and Lord of the Rings. UFO religions, on the other hand, use Science Fiction to explain how we got to where we are. What's wrong with that?

This doesn't mean that every sect and cult should be accepted as a legitimate religion. I only referred here to one aspect of the matter. There are so many other aspects, such as how the religion treats its believers and whether or not it puts them in harm's way (e.g. making them commit suicide or preventing them from taking vital medication). I don't know enough about Scientology to judge whether it should be accepted as legitimate.