wow...
better put my flame-retardant knickers on
in my family, we don't celebrate christmas. we celebrate the winter solstice, which christmas was based on. (we also celebrate summer solstice, and the two equinoxes as well)
I intend (after I persuade their father to talk sensibly to me about it, where he may change my mind) withdrawing my children from the "christian based worship" which assemblies are supposed to be about, as we are NOT christian.
However, I have no objection to them learning about religions, just being made to worship any god by default.
I won't object to my children being in a nativity play, any more than I would object to them taking part in a replica sedar meal for passover, or any LEARNING activity about any religion (except anything harmful to them, which I can't see a school doing anyway). I would object to them being told "this is what's true" about the beliefs involved. I would talk to my children afterwards to make sure they understood that it was just what some people believe.
I accept that the winter break is called the "christmas holidays" and thus the play most schools put on then is called the "christmas play" - while we aren't christian the fact is that all the countries which make up the UK are culturally christianity-based.