Here's the usual War-on-Christmas stuff from Fox News: Students at a Little Rock, Arkansas public school were invited to a performance of "A Charlie Brown Christmas" at a local church (and by invited, I mean notes were sent home from the school, and a school bus was to shuttle kids to and from the performance). Parents could opt out and students were not required to attend, but "at least one parent objected to the field trip and contacted the Arkansas Society of Freethinkers, a self-described community of atheists, agnostics and humanists."
The article describes this as "a constitutional controversy." It is unclear from this article, however, what the Arkansas Society has done to spark a "controversy" besides posting about it on their Facebook page and talking to the local TV station (which you'd think conservatives would applaud, since they're supposedly such big supporters of free speech), and in fact the school system says there is no controversy. Perhaps the Arkansas Society is threatening to sue, but this is not stated in the article.
There are the usual complaints in the comments ("atheist(s) LOVE to ruin Christmas for everyone, especially kids," "Christmas is Christian holiday. If you don't like it get your own," and so forth and so on). But come on. Pretty much anyone who's ever lived in America for more than a couple of years is aware that "A Charlie Brown Christmas" has a heavy-handed Christian message. By treating it as a field trip and using school buses to shuttle the kids back and forth, the school system is in fact giving the appearance of promoting Christianity. And the school system knows they shouldn't do that; the communications director for the school system was quoted as saying "the school district does not 'promote or encourage students to support any religious affiliation.'"
No one is saying that parents shouldn't be allowed to let their kids watch "A Charlie Brown Christmas" on TV a thousand times, or that the church shouldn't be allowed to give the performance. They're simply pointing out the school should not appear to promote a performance with a strong religious message.