I thought about the "is she making a theological argument" angle for a while and concluded that she is because by invoking the Christian belief she is, I believe, lending it credence. I don't think the court can use theological belief as part of a decision without implicitly making a statement on court's view of the truthfulness of that belief. And that's plainly not allowed under Ballard.
On the other hand if she was doing as you say and simply talking about local perceptions she certainly worded it clumsily. I didn't get that sense from her statements as they were written in the article.
She didn't preface her comments with "There are alot of Christians in this community and they believe that Jesus is the messiah..." It sounded to me like a statement of fact though I haven't read the full text of her comments, only what was reported in the media.
I agree with you I'm not sure the perception issue matters in the case. I would go one step further and say I'm not sure I want judges to have that level of authority over parents at all.