if its good its god, if its bad its the devil.
Putting aside the question of whether such deities exist, instead we need to focus on the ambiguity of the words good and bad. Neither word has an absolute meaning. Each person, pending we have free will, makes constant determinations as to what they believe is good and bad. Sartre was fond of making the argument that without god man creates himself. I make a much looser assertion.
A perfect example is food. Say you think prime rib is good. To a vegan, prime rib is bad. It is both good and bad, ambiguous.
To a catholic, god is good and the devil is bad. To a satanist the devil is good and god is bad.
What about murder? Murder is the willful taking of life. Can murder be a good thing or is it always bad? A poor analogy would be the war argument, that soldiers willingly murder people, but they don't. They follow orders. Taking ones own life is murder and therefore bad. But its not. In certain cultures committing suicide is respected and therefore good.
And if god exists, then god takes our lives willfully, being the supreme arbitrator of life and death. So to rewrite the statement of the television ministry:
If its good it might be god or the devil, and if its bad it might be god or the devil
