But still, belief should trump fact when deciding what to teach?
A difficult question. Positive demonstrated fact should trump blind belief. However, in a situation where truth is in question, or where scientific facts are incapable or have been unable up to this point to prove a truth, then the majority should have the sway in what to teach.
In the Middle East, the overwhelming majority believe that Allah is god, presumably because that idea has been convincingly demonstrated to be true. I presume you wholeheartedly support the teaching of Islam wherever there is a majority of Muslims? I presume further that in any country where the Christian population becomes a minority (as is almost now the case in the UK) you would strongly support any moves to teach that Christianity is false?
Yes, I agree. In that situation Islam should be taught.
With your second point, I also agree to an extent. I agree that in a country where Christianity has become a minority, I would support the motions made by a fairly elected non-Christian official. Though, I would continue to protest in whatever way I could legally the points I disagree with.
If this non-Christian official was a good one, however, I would expect him to understand that Christianity is still a large minority and not to entirely disregard or bash Christianity in his choices. Perhaps, he would point out Christianity as an option but emphasize his beliefs. Or, rather than directly teaching that Christianity is false, he would merely teach that his belief was correct or believed by the majority.
To answer your question, I would entirely support the right of a non-Christian official to make decisions for the wider population but I would continue to protest the ones I disagree with.