I put off writing the first Left Behind book for a year because I got invited to assist Billy Graham in his memoirs, and had we known what we were putting off for a year, we might not have put it off.
Good fiction must be entertaining, but what makes fiction special - and True - is that the realness of a novel allows it to carry a larger message.
In the prequel we're going to tell about the characters before Left Behind, and the book would end with the rapture instead of start with the rapture like the first one did.
When I was a junior camp counselor and it was my job to tell the campers a bedtime story or devotional, I would tell them a rapture story.
Fiction has a unique role in conveying Truth. In fact, only fiction that is Truth with a capital T is worthwhile.
Tim sends me a fairly ambitious workup in notebook form noting the passages we're going to cover and the chronology of the biblical events, and his commentaries on those things he's read and written.