On the one hand, it has a list of issues that tend to bother people: anger, addiction, getting motivated in the morning... no doubt there's one for eating too much chocolate, enjoying sex, feeling lazy. Leave the Devil out of it and I think we can admit that lots of people have habits they would like to control or change. On the other hand it has a database of scriptures from the Bible, which get more or less matched up with the habits on the list. A random one will be distributed to the user on demand, or even spoken aloud at regular moments if you set it up that way. Well, again, whether it's the Bible or not, it's basically a load of supposedly motivational, inspiring self-help literature.
Take the religious mythology out of this one, and you can imagine it as any old self-help app, book or technique. I expect it works about as well or as badly as they would, which means its performance should be mediocre at best. But, if you happen to be in the motivational field, it sounds like a really good way of
Heads up to Ed Brayton at Dispatches From the Culture Wars for pointing me in the direction of Shut Up, Devil!