Never stop having doubts. If you ever do,it will be because you've stopped moving forward, and at that point, God will step in and pull the rug out from under your feet, because that is his way of controlling his chosen ones, by making sure they always follow their appointed paths to the end. If, for any reason, we stop, whether out of complacency, laziness, or out of a mistaken belief that we know enough, he forces us on.

On the other hand, you must be careful never to allow doubt to paralyze you. Always take the decisions you need to take, even if you are not sure you are doing the right thing.

Paulo Coehlo