What the Devil Were They Thinking?

Please excuse the bad pun, but what the hell were the prosecution and the judge thinking when they decided that evidence of a defendant's Satanism was admissible at his trial for killing his infant daughter? Apparently, they weren't alleging that she was killed as some part of his satanic practices (in which case it clearly would be admissible), just that him being a Satanist made it more likely that he would kill his sick baby. Huh? Did I miss the part where this is nothing but propensity or character evidence? I don't know much more about the details of the case, but if they had a strong case without the Satanism evidence, why taint the conviction by throwing it in there? This seems like an act of desperation in a weak case. Nice to see the judge play right along. Unfortunately for them, an appeals court has overturned the conviction, which, frankly, seems like a no-brainer.