The show was a cute concept. By all means, it had some bugs in it, but most great animated show take at least the first season to find their footing. However, because of the religious aspect, "God, The Devil, and Bob" never got its chance to get off the ground.
The show promoted a positive look at family life and relationships. It was mature and respectful. However, many people objected to having God and the Devil as friends. They focused on one minor point rather than the larger messages that the show promoted through its humor. It was never disrespectful. It never got its fair shake, despite being clever, funny, and thoughtful. At least it made it to air, which is better than nothing.