I'll be honest with you: As a Christian, I don't necessarily mind films with an anti-Christian message if it's well-directed, a good script, well-acted, etc. My faith isn't so weak that I can't stand someone criticising it, or expressing their own views. I don't consider it my job as a Christian to convert anyone. Preach the gospel, yes, but how people respond is between them and God. I don't go around twisting anyone's arms.
The point is, I may hate the message, but I can admire the craft. However, I didn't think Mamma Mia worked on that level either, so it just gave me an excuse to be even more irritable. Then that incident with my former church happened, and I got even more annoyed with it. Just as well I like ABBA. If it had been Celine Dion songs I'd have declared the film to be the Antichrist.