What does my doubt teach me about my faith?

Just because I go out on a sailboat doesn’t mean there will be wind. And should a favorable wind come, I cannot be certain from which direction. I can only trim the sail to use it to power the boat according to the skill I have. My experience of perception is that it is, at best, fickle. I no longer doubt much other than myself. Gravity works (somehow). The forces at work outside myself are just that. My task is to find a path through each moment doing as little damage as possible. So the contradiction is baked in. I cannot know the ends only the means. All the great teachers seem to point to this simple fact. I often doubt my understanding of the principles and facts. This does not affect my faith in the process. For it seems when I come down to it that the practical faith I encounter each day keeps me from going mad. And, for what it’s worth I will add, those I have encountered in my history harboring a deep certainty make me nervous.