I fear it's because religion is man's attempt to reach God, and when he feels he has succeeded, he cannot abide anyone else's claim to have done the same.
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.
I've written enough books with real celebrities, such as Walter Payton and Hank Aaron and Billy Graham, to know that fame looks good only to people who don't have it.
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.