I am very surprised by the hypocritical views on this thread though I am happy to be corrected if I have assumed wrongly. Please tell me, those saying that it isn't a problem and just to go along with it, would you, HONESTLY be fine with it if you discovered that at the end of assemblies your sons were given a prayer rug, had to face towards Mecca, remove their shoes and repeatedly prostrate themselves (going from standing to bowing, kneeling then face to floor) whilst reciting passages from the Qur'an?
It is perfectly acceptable to ask children to pray, but only in one way? To a Christian god? One can teach about religion so that the children have a full, well rounded education, but to force them to act it out, to take part and actively pray should be banned whatever religion it is.
I am now an atheist after being raised Roman Catholic. I think that RE should be compulsory because it gives us an understanding of other people and cultures, literature, art and history. The teacher in this case is very wrong. It's not their choice to override a parent's wishes.
My own DC take part in Christian religious ceremonies at their non-denominational school and I haven't been too bothered because I am happy to counter at home what they have been told is fact by giving them real, logical facts, just as I would if someone told them that the Earth was flat or that vaccines were bad.
Noah's Ark for example caused a few laughs with me when I asked if the kids knew how many men lived to 600 years old and could build a boat big enough for a billion or more animals for over a month. I also pointed out that breeding closely related animals causes genetic defects which meant that two (or even a group) of every animal would not be able to successfully repopulate the Earth after a so called benevolent god threw a temper tantrum and killed every man, woman and baby, innocent or not.