This is amazing! As an ardent atheist, I've often heard the argument that without God, moral action is not possible--an absolutely incredible counter example has arisen. According to newly discovered letters, Mother Theresa--famous and tireless activist for the poor, Catholic saint, and all around incredibly good person--was "plagued by doubts" about the existence of God, and may have spent more than half her life as an unbeliever. The letters are full of gems like: "Where is my faith? Even deep down… there is nothing but emptiness and darkness... If there be God — please forgive me." and "What do I labor for? If there be no God, there can be no soul. If there be no soul then, Jesus, You also are not true."
Again, incredible. Though she came to doubt the existence of God, she continued to labor for the good of others to great detriment to herself. Take that, Christian apologists!