From the "Dragonlance" series, the first book has one of my favourite metaphors for faith. Always having gravitated to fantasy gaming or novels because the gods there really do exist (heh) stuff like this can set off the water works in me.
Some context first. In the series, the gods of good, evil, and neutrality after sending a mountain of rock crashing into the world hundreds of years ago turned away from everyone. Since then, false religions worshipping false deities have sprung up everywhere. But the true divine healing and blessings are still absent from the world. Until 'Goldmoon' 'rediscovers' them and becomes a cleric of the old goddess of healing:
..."Maybe not." Tanis smiled. "Goldmoon is a cleric. She can heal him."
"Perhaps, perhaps not," Maritta said skeptically. "I wouldn't want to
chance it. We shouldn't excite Elistan with false hope. Let him die in
peace."
"Goldmoon," Tanis said as the Chieftain's Daughter came near. "This
man wants to meet you." Ignoring Maritta, the half-elf led Goldmoon
over to Elistan. Goldmoon's face, hard and cold with disappointment
and frustration, softened as she saw the man's pitiful condition.
Elistan looked up at her. "Young woman," he said sternly, though his
voice was weak, "you claim to bring word from ancient gods. If it
truly was we humans who turned from them, not the gods who turned from
us as we've always thought, then why have they waited so long to make
their presence known?"
Goldmoon knelt down beside the dying man in silence, thinking how to
phrase her answer. Finally she said, "Imagine you are walking through
a wood, carrying your most precious possession-a rare and beautiful
gem. Suddenly you are attacked by a vicious beast. You drop the gem
and run away. When you realize the gem is lost, you are afraid to go
back into the woods and search for it. Then someone comes along with
another gem. Deep in your heart, you know it is not as valuable as the
one you lost, but you are still too frightened to go back to look for
the other. Now, does this mean the gem has left the forest, or is it
still lying there, shining brightly beneath the leaves, waiting for
you to return?"
Elistan closed his eyes, sighing, his face filled with anguish. "Of
course, the gem waits for our return. What fools we have been! I wish
I had time to learn of your gods," he said, reaching out his hand.
Goldmoon caught her breath, her face drained until she was nearly as
pale as the dying man on the cot. "You will be given time," she said
softly, taking his hand in hers.