Supporting groups that want to send home religious literature with schoolchildren; in one case, the government helped win the right of a group in Massachusetts to distribute candy canes as part of a religious message that the red stripes represented the blood of Christ.
I think these types of things are probably best fought with a little gonzo action. Just overload the system with Wiccans, Pastafarians, Rastafarians, Mormons, Scientologists, Satanists, Discoballmouseatarians, and every other religion which might not be seen as a "real religion" by the local powers that be until they begin to see that maybe this isn't such a good idea after all.