Every now and then I have doubts. It could be a number of things, but sometimes it's: is Jesus REALLY who He claimed to be. Yeah, I know, that is a big doubt. Seriously though most people have these kinds of doubts. One thing I do to overcome this particular doubt is to put myself in Jesus' disciples shoes. I imagine that I am one of the Twelve. All of the miracles, all of the compassion, all of the love He had. Witnessing those things would have been ... amazing. These men wrote the majority of the New Testament and after putting myself in there shoes its easy to see that my doubt is foolish. Inspired by the Holy Spirit they wrote His story for us.
If you ever have doubts just put yourself in the shoes of a disciple and start to imagine all the things you would have seen. It's ... amazing.