Doubts are good. It means you are alive and searching. One does not become a believer overnight. He thinks he is a believer; then something happens in his life and he becomes an unbeliever, after that, he becomes a believer again and then an unbeliever again, and so on. Until we reach a certain stage, we constantly waver. This is the only way forward. At each new step, we come closer to the Truth.