What makes you believe in god?

First I would say that I'm a catholic because I was following my family's beliefs, now being grown up, deciding on my own, I've sometimes doubted about what I believed in and why. I'm the type of person that likes to know how things work, why things happen before getting into out of the ordinary, extra normal, supernatural, religious points of view or arguments. But one thing I could say is that me believing in God, makes me have that "something", peace of mind, calmness, spiritual moment everybody needs as a person. Even if someone is an atheist, some type of practice they would require to have that inner peace.