Our beliefs inform our actions, that much is certain, which is another reason to ensure that our beliefs are rational so that our actions will likewise be rational.
If you got 10 Christians in the same room, even Christians from the same denomination or the same church, you'd still get 10 different opinions on what their beliefs ought to be. There are over 30,000 different sects of Christianity worldwide, yet if we were honest, there are as many versions as there are Christians, the same goes for Islam, the same goes for Buddhism and Shintoism and every other religion. There isn't a single version of any religion that everyone who professes that religion subscribes to.
But everyone is supremely convinced that their version, and only their version, is the correct one, which I find strange. You'd think that all they'd have to do is talk to each other to realize that all of them have the same position on the "truth". They can't all be right but they can all be wrong.