I think "Dammit, Alabama!" and that it's blindingly illegal. It carries with it the idea that these criminals would not have committed their crime if only they'd gone to church every week (HA), it very likely discriminates against any but a Christian church (or, perhaps, Jewish), and, while it would save the state money, it is not actually allowed by the constitution, what with the whole separation of church and state bit. You want to give them an option? Here's a thought: have them volunteer at a local charity for a year. Same frequency, same ability to have someone check, same cost to the system... and they're actually doing some good for the community.
(Of course, I also think it would be hilarious to be sent to a Church as a court sentence and just make as big a nuisance of myself as possible. But that's another story entirely.)
Just FYI, there is no such thing as a Jewish Church, but I'll bet you serious money that Jewish, Muslim or other religious institutions were not included.
And your idea about community service is MUCH superior -- why didn't YOU run for govt. office in Alabama? They NEED people like you! Even though you'd have no chance of winning!! :-(
By the way, we DO have community service in Nevada -- so it's not unheard of.