That's it exactly. This is very common with cults, they have an external doctrine/image and an internal "members-only" doctrine.
If you ask a scientologist what it's all about, they'll say something about how it opens you up to your potential and helps you to understand your spirit etc. etc. Once you get in deep enough is when all the insane stuff about aliens and Xenu starts.
Same thing with the Mormons. When they come to your door they won't tell you that they all expect to be made into gods as a reward for their faith.