I just finished reading Reaching for the Invisible God by Philip Yancey, so (just to warn you) you will be subjected to quotes from it for the next couple weeks! Here is the first, which I chose because I feel like it is talking about me.
A person reared in a Christian home, who has absorbed the faith along with other family values from trusted parents, will one day face a crisis that puts loyalty to the test. She may have had religious experiences, may have felt something of the closeness of God. Without warning, that sense vanishes. She feels nothing except doubts over all that has gone before. Faith loses all support of feeling, and she wonders if she has been living under illusion. At such a moment it may feel very foolish to hold on to faith regardless. Yet, as Ignatius [Loyola] counsels, now is the time to "stand firm." Faith can survive periods of darkness but only if we cling to it in the midst of the darkness.