We let people determine what can be taught. Very few people are free of ideologies, whether they be religious or secular. Find me a living, breathing human being who has no personal biases, and I'll ask the doctors why a patient with absolutely no higher brain function hasn't been taken off life support.
One of the things that we, as conscious human beings, should do is strive to recognize the lenses through which we view reality. Yes, everyone has personal biases but it is possible to understand those biases, examine decisions that you are making and recognize their influence on your decision making process. This allows us to make more objective decisions. If someone is not able to do this then IMHO they should not be in a position to make decisions that have significant influence over other people, such as judges or educators.