Unfortunately, common knowledge is not that common in some christian communities.
Which communities think that tree decorating was invented by christians?
It always cracks me up when christians claim that Jesus is the "Reason for the Season". If we really went to the source, paganism is the "Reason for the Season". Just tell one of the Christmas defenders that and watch their feathers ruffle.
But that's just because they got there first, because they were the oldest. Nowadays tho, we're not putting up christmas trees because were maintaining pagan rituals, we're doing it because christians adopted those rituals and injected Jesus into them. So the reason we have a christmas tree today, is because of the christians, ergo Jesus *IS* the reason for the season. (even tho he's not the source of the ritual)
Its kinda funny tho, that on one hand we have that Jesus isn't really behind the christmas tree, and on the other hand we have not wanting to call it a christmas tree because Jesus is behind it