I got to thinking last night and wondered if the "Christian" bookstore isn't a somewhat recent phenomena. I don't recall seeing any around when I was growing up.
I don't remember any either, but I had what some would call a 'protected childhood'. There's a lot of things I don't remember that were likely quite commonplace in those days.
Of course, there was inspirational and biblical fiction, but it was published by the trade publishers and sold in "regular" bookstores. If you mentioned Christian publishing you were probably referring to a denominational or ministerial publishing arm that produced tracts and such.
I think you'll find that a lot of the trade publishers and regular bookstores were more tolerant of Christian-themed things back then. I'm not sure why that is, except that some of the people in the business were Christians (Tolkein, for example, along with C.S. Lewis, were both devout followers of Christ). So it would make more sense that the big houses and the regular stores would carry more Christian stuff. Sometimes, they still do. It's just harder to find because the regular stores sell so much other stuff on top of Christian materials.
Now that I think about it, the big studios made biblical movies in those days, too. Now we seem to have "Christian" film makers.
In the book
DeMille: The Man And His Pictures, there was an interesting thing about the first big biblical movie, The Ten Commandments (the 1923 silent version). One of Hollywood's big-wigs asked Cecil B. De Mille, rhetorically, "You want to pour millions of dollars into a Sunday School lesson?"
It was shocking to the people at Paramount, but De Mille, who as I understand it was a committed Christian himself, pushed it through. The Ten Commandments became a huge seller, and started the rise of the big-budget Biblical films.
But the fact remains that a lot of Hollywood's higher-ups looked with quite some dismay at the idea of a Bible film. Were it not for those who saw the potential, I rather doubt there would have ever been a big-budget Bible movie in the first place.
Is this a marketing thing, or an attempt by some groups of Christians at separation from the mainstream?
I think what this is, is a desire to get the Gospel out in any way possible. Paul wrote "I have become all things to all men that I might by all means, win some." It makes sense to me, therefore, that a lot of these film-makers are out not for the money, but for the Cause of Christ.
And some Christian films have made decent success in theaters. The Omega Code (TBN Films) was an excellent example of that. It lasted a decent amount of time in theaters and was fairly competitive. But I think many Christians have become disillusioned about films depicting Biblical and other Christian themes because of what some believe is an anti-Christian bias in the industry.
So really, Christian film-makers, I think, are trying to fill in a gap that the secular world would just as soon leave open. Also, I think some are trying to reconcile old differences of opinion concerning movies and Christianity (i.e. "If you go watch Ben-Hur in the movie theater, and Jesus comes back, you'll be left behind" was something well-meaning Christian parents used to tell their children to keep them out of theaters.) So there really are reasons for Christian film-makers to come together and at least try to produce good quality films about the Savior, that don't have to do so much with money or marketing.
Good questions.
--Sean