In Mark 4:9-12 it says, "And he said unto them, He that hath ears to hear, let him hear. And when he was alone, they that were about him with the twelve asked him of the parable. And he said unto them, Unto you it is given to know the mystery of the Kingdom of God: but unto them that are without, all these things are done in parables: That seeing they may see, and not perceive, and hearing they may hear, and not understand; lest at any time they should be converted, and their sins forgiven them."
Jesus taught in parables to reach those who were not versed in the word, those who might not be saved. He did it because the parables spoke to people in terms they could understand. Today this concept is why people write Christian fiction. To wrap Biblical principles in a good story that will maintain the attention of the reader and will put the principles in terms the reader will identify with.
It doesn't mean all Christian fiction will contain a strong message or even a salvation message. The degree of faith content can range along a scale of a very strong message to very little faith content at all. What is important is that it engages the reader, pulls him into the story and keeps him there so he wants to read more of the same.
It is the process of planting seeds, and a very small seed can grow to be a mighty plant. I've been involved in the planting of seeds for a long time. I seldom get to be in on the harvest, those in the ministry get much more of that, though I cherish the few times I have been privileged to be in on the harvest. Yet those who do harvest are dependent on those who plant the seeds and nurture them along the way until the harvest is nigh. This is the business of the Christian fiction writer, to plant and nourish . . .
. . . and above all else, tell a good story that will leave them wanting more.