At the beginning Mimi, art model, loves the painter Paul; Georges, a banker, loves Marie, and they are bethroted. In the end nothing has changed. In the middle there has been some fuzz, all caused by the devil himself, in the sembiance of dr. Müller: he wants to show that it's not true that "Evil can never overcome Truth", as everybody seems to think.
In the middle Paul and Marie become lovers. Is it true? Yes, it is. Is it evil? No, it is not. In the end, as I said, George loves Marie, and they marry; and Paul and Mimi reunite. Is it true, is it evil? As above. I won't say the devilish dr. Müller failed to prove his point, rather that the point cannot be proven at all, no example having been given of Falsehood or Good, in particular.
Moreover: we are told and showed that the devil/Müller has done all the mess. But it could well have happened also without him, all by itself, as it happens in life, either for believers or agnostics. In that way the protagonist himself is out of the picture.
