Mother Teresa expressed grave doubts about God's existence and pain over her lack of faith...
Where is my faith? Even deep down ... there is nothing but emptiness and darkness ... If there be God--please forgive me. When I try to raise my thoughts to Heaven, there is such convicting emptiness that those very thoughts return like sharp knives and hurt my very soul ... How painful is this unknown pain--I have no Faith. Repulsed, empty, no faith, no love, no zeal, ... 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.
Those were Mother Teresa's words, or at least I'd like to think they are accurate, mostly because it reveals the genuine struggle of this woman we are so eager to idolize. Humanity. Doubt. Reason. These are brutal realizations she expresses.
Chistopher Hitchens goes to great lengths to refute the common perception of Mother Teresa, knocking her off the pedestal, and kicker her while down. He may be right; I don't know. But her quote above is enough for me.