I am a firm believer in the separation of religion and state and in secular education. However, I live in a country (Egypt) with a national religion (Islam, with Christianity recognized as the religion of some citizens), which does not have such a separation as a core value. Therefore, religion is a subject taught officially in all schools here. Muslim kids are taught Islam and Christian kids are taught Christianity.
My son is in the first year of high school and came home two days ago telling me that the religion books had not been issued (the textbooks are government-written and are very noncontroversial and innocuous - I check them every year and monitor what they teach). The teacher has picked up the slack by preaching very extreme ideas to the kids that are in no way part of the official curriculum:
* A kid with longish curly hair who was wearing athletic wrist bands was told that his "long hair" was "haraam" (forbidden) because it made him look like a girl and the wrist bands were also forbidden because they were like girls' bracelets.
* The 5 girls in the class, 4 of whom do not wear a head scarf (they are 14 year olds) were told that if women don't wear the headscarf throughout the month of Ramadan their prayers will not be accepted even though they put the scarf on to pray.
* A kid who told this teacher that the scarf idea was wrong was told to stand outside the class for the entire period as a punishment for saying the teacher was wrong. When he came in and asked for water and my son asked the teacher if he could give him a drink from his water bottle the teacher said no.
* The teacher did not back any of his weird ideas up with any "Islamic proofs" (verses of the Quran or sayings of the Pprophet Muhammad, upon him be peace) but just stated them as facts.
I called the school the next morning and talked to the principal, telling her what had happened in the classroom and making the following points:
* The religion class should be completely restricted to what is in the government approved curriculum.
* The teacher is an Arabic language teacher and has absolutely no credentials to teach religion other than to cover the material in the book.
* The school's job is not to take over from parents and students on personal issues like dress/hairstyle.
The principal was horrified at what I told her and promised that the issue would be dealt with. Yesterday when my son came home I asked him what had happened in Arabic class. He said the girls in the class had tried to raise the discussion of the scarf issue again and the teacher had refused to discuss it. I hope he was warned sufficiently strongly to mind his own business and keep his extreme and weird attitudes to himself.