And learn about the basic principles upon which they were all constructed.
If you're really interested in this subject, look up Ken Wilber:
I'm not a big follower of "Integral Theory" per se, but this guy does a great job of showing what the foundational principles of spirituality are by showing all the things most religions have in common, and stripping away the dogma.
Don't get me wrong, I am not proselytizing. Ken Wilber is not my guru. But there was a time when I was struggling with these kids of questions myself, and his theories really helped me make sense of things.
edit: replaced link with a better option.