The main point of school is to prepare people for their future careers. Learning creationism does not help anyone for their career except future priests and theologians.

What is the difference between a child choosing to learn about religion on their own outside of school and them choosing to learn about in school in a class? They are still making the same decision, just in a different context.

I do not believe that students should be allowed to opt into a class about creationism since there is no scientific grounding behind it. The only thing children should learn about in schools are things that have significant evidence to support them.

I think that all religions are already being taught in public high schools. In history classes most of the major religions' beliefs are already discussed although it is just the basics. However, all public schools ever do is teach the basics. Nobody learns advanced physics in high school but rather they have to go to college and major in it to learn about the subject in detail. It is the same with religion, everyone learns the basics but in order to learn more people would have to learn about it in college.