Ok, I know I could very well get bashed for my opinion, but I agree with that ruling. I will say, as a sort of disclaimer, I am really jaded with the entire Columbine thing, and especially the parents of the victims, since I live in the same area (I'm maybe 10 miles north of the actual school) and we hear everything that goes on with this.
First of all, Eric and Dylan didn't necessarily target someone for being Christian. They targeted everyone. Yes, they did ask one of the notoriously religious girls if she believed in God. I don't necessarily consider that targeting, just being cruel. Of course, her parents who made all kinds of money from the book about her faith don't see it that way. If she wasn't targeted, she wasn't persecuted, and the book would have been nothing.
OK, back to the subject at hand. I understand that the parents wanted to memorialize their children with religous themes. That probably would have been OK to put like a small cross by their name or something. However, Christianity was the primary focus of the tile, not the child's name.
Would you still think it sad if a Satanist wanted to put a tile with upside-down crosses on it? Or what if one of Eric & Dylan's friends made one with nazi swastikas on it for them? It's all a matter of personal preference, and the line has to be drawn somewhere.
And before anyone calls "hyprocrite" for my views on the Pledge - there is a big difference between an ambiguous God and specifically calling out one religion.
Sorry for the rant, but I feel pretty strongly about the whole Columbine thing.