It depends. Do you doubt and then simply say, “since I doubt, it must not be true;” or, do you doubt and then say “I doubt, and so I will search to see if there are answers.”?
Many people take the first route, believing that their doubts are enough evidence to prove their faith is wrong. That is bad, and it is irrational. But it is also easy, which is why many people go that route.
The second route is completely acceptable, and I would argue it is natural given our fallen state. Approached properly, this sort of doubt can lead to a greater understanding of God.
If you feel doubt, try to figure out where that doubt is coming from, and then look to see if other people have had those doubts and found reasonable answers for them. In pretty much every instance, there are probably answers to your doubts. ^^