I do not speak for all Brights, but I oppose it on at least two grounds.
Foremost, it is contrary to the constitution. Public schools are government run and presence there clearly implies approval and support. Those that believe in religion work day and night to infuse their brand of religion into the government. Schools are one place they are trying to open up a crack.
Second, as I observe the effects of religion, I am becoming more opposed to it by the day. I cerainly do not want it taught in schools, constitution or not. If you want to argue that, please check out the history of religion before you post. It is downright horrible.