Religion is taught and practiced rigidly. This can help pull people together under a common faith. Most of the time it is used to control people. It is highly effective because religion is passed down through families. People become brainwashed at a very young age, which makes it more difficult for them to see past what they have grown up with.
A belief system does not have to rely on blind faith or rigid principles. It can be based on life experiences. A belief does not need to be forced on anyone as it can exist as a personal choice. I have found having some sort of belief adds direction and purpose. It is never going to be possible to known all the facts.