You don't even have to get into the intolerance of Christians to appreciate how completely stupid this is. Here you have a season which revolves around a particular holiday, and the reasons for celebrating that day can't even be acknowledged, in fact, we need to go out of our way to ignore them because they might be considered "offensive." Now, since we're supposed to respect "diversity," how can the recognition of somebody else's customs ever be "offensive?" That recognition is supposed to be the greatest good to these idiots.
Unless, of course, you aren't really interested in diversity at all, but rather, in destroying the cultural identity of your enemy.