What do you think about humans claiming that the true meaning behind the bible is to prepare humans with rules for joining a Federation of aliens?

LOL..WTF! Basic instructions before leaving earth?

Either be dead or have your passport on standby.

I like it. I never heard that before, but I find it entertaining. Just like I like the alien idea explaining the pyramids in Egypt and Latin America.

It’s about as rational as any other reason to consider the book a credible reflection on reality.

It’s absurd. The word “bible” is derived from the Latin “biblia,” meaning “books.” It’s not a title, it wasn’t planned, and the word is in not restricted to Christian scriptures. What you are talking about, then, is just a classic example of a backronym.

Considering the content, I would doubt that very much.
If it were true, however, you would be well advised to start developing phasers and photon torpedoes, because you are going to need them.