Like the secular market, the Christian market is one broad category with a zillion sub-categories. There's Christian Romance (Rachel Hauck, Becky Wade, Tracie Peterson), Christian Suspense (Terri Blackstock, Ted Dekker), Christian - Amish (Wanda Brunstetter, Beverly Lewis), Christian YA - (Robin Jones Gunn, Melody Carlson) etc etc etc ... So before you start market research, I'd get more specific with which segment of the market you need info on.

Those authors were off the top of my head, so there are certainly others that are what you're looking for. Thank goodness we have Google --- I'm also doing market research and platform blah blah blah... I can't fathom trying to figure this stuff out without the internet!