Not being an artist I cannot help you in that arena, but as a writer I take some interest. I have two cautions for you: initially, the subject you have chosen is a very touchy one. That is not advice, merely a warning. My other caution is more concrete: with any redemption plot, you constantly run the risk of straw-manning non-christians or becoming seriously cheesy. Of course, when these things are escaped such works can be good indeed, but I believe they should be kept in mind.