There's A Red-nosed Reindeer In The Nativity Scene

For whatever reason, I feel like I've been exposed to an abnormally high rate of atheistic holiday messages as Christmas approaches. They haven't all been entirely hostile to religious celebration (though many certainly were), but they've all encouraged viewing Christmas as a secular holiday.

The primary point that seems to be made in advocating Christmas as secular is that Christians co-opted pagan rituals for their holy day.

I guess maybe I'm a little obtuse here, but, so what? I don't see how that in any way de-legitimizes Christmas as a Christian holiday, or removes any religious significance. Christmas is both secular and religious. If some people want to celebrate it in more religious fashion, the secular nature doesn't diminish that meaning. If others want to celebrate it in more secular fashion, the fact that others attach religious significance to the day should have little impact.

And yet both the secularists who cry out about the non-religious origins and the religious folks decrying the "war on Christmas" are equally guilty of trying to deprive the other side of their holiday. We have secular holidays (4th of July, Groundhog's day). We have religious holidays (Pentecost, Opening Day). And we have joint holidays (the perfect example is below in my song quote). The joint holidays cannot be bifurcated. Why do people try?

Ok, I realize this post was pretty crummy. I think there's some solid ideas here, but I didn't really have a focus. I apologize. Still, I'd like to see if there's some discussion that can be generated here, since I feel like I've got some digging to do into this topic. So here's a couple quick questions:

Why do secularists point out that Christians co-opted pagan holidays? What are they hoping to achieve with that point? What do they achieve?
Is there a way to bifurcate the holiday? Should we even try?
Why do people want to call it a singularly religious or secular holiday?

Ok, go:

Santa Claus knows we're all God's children