I once heard Randy Harris say that the opposite of faith is not doubt, but apathy. Faith requires actions based on that faith. Or as James said, "Faith without works is dead."
Now word comes out that even someone as looked up to as Mother Theresa had here own doubts, as Time Magazine has reported. I know that there are many who have doubts about many things that we've believed or been instructed to believe. However, my prayer for myself and for all of us is that those doubts will not stagnate us into apathy, but that the actions that we take to bring God's justice and peace into His world will continue in spite of the doubts and not "feeling" God's presence.