At some point in their writing career, many Christian authors express a desire to write a book that would reach the un-churched. That desire is a completely honorable and wonderful goal, just as any believer should desire to represent Christ in their lives in such a way that unbelievers would ask them questions about the hope that is in them.
However, the inference by such statements as “preaching to the choir” is that writing to churchgoers is somehow less desirable. I know the intent of those authors is to have their books used for pre-evangelism, but unfortunately, when most Christian authors use the term “cross-over” to describe their book, it is code for “leave out anything Christian”. I am not sure this is a wise use of your time unless you are very gifted and unique writer.
Indulge me for just another minute before you start writing a reply, hitting me with examples of Lewis, Tolkien, Sayers, MacDonald, Bunyan, Tolstoy, Chesterton, etc.
First, God Almighty can and does use whatever he wants to get people’s attention. I hear God even used a talking donkey once. Second, it is a matter of fact that the books that God has used most frequently for evangelism have testified strongly to Jesus Christ and the power of the Gospel to change a life. Consider these: