Side 1, Chapter 13 Vader is talking with the officers of the Death Star, in particular, General Tagge.

GT: This station is now the ultimate power in the universe. I suggest we use it.

V: Don’t be too proud of this technological terror you have constructed. The ability to destroy a planet is insignificant next to the power of the Force.

GT: Don’t try to frighten us with your sorcerer’s ways, Lord Vader. Your sad devotion to that ancient religion has not helped you conjure up the stolen data tapes, or given you clairvoyance enough to help you find the rebels’ hidden fortr…<Vader uses the Force to choke Tagge.>

V: I find your lack of faith disturbing.

1) Tagge tells us that the Force is a religion.

2) Vader tells us that the Force requires faith.

3) In the novelization of Star Wars, Tagge does not refer to the Force as a religion -- he calls it an ancient "mythology." But if we consider just the films to be canon, we have to accept that the Force is the basis of a genuine Jedi religion. Maybe even more so, now that we’ve learned about midichlorians. Have a look at this:

http://user.xpoint.at/e.lebic/jedilib/midichlorian.htm

In spite of that, though, it possible we’re to infer that the common people in the GFFA, Muggles like Tagge, harbor a basic misunderstanding of the nature of the Force? They consider it a religion because they’re not equipped with enough midichlorians to understand its very secular, scientific, biological nature? I think it’s possible that’s a possibility too. So basically, I just don’t yet understand what the Force is all about, and I suspect I may never understand.

(Aside to Nesha, if she’s made it this far: I can never think about this subject without picturing Darth Gary spitting his Coke right there in the theater, when the subject of the midichlorians first comes up.)