Why teach them anything at all if the truth will seep in anyway?
Besides, I bet I can think of a looong list of human beliefs once held dear by many people you'd strongly object to being taught in public schools. It's not a free speech issue, because it's paid for by taxpayers, and kids are forced to attend it.
Teach them reading, writing, and arithmetics. Everything else can be learned independently (which is too easy these days) or in vocational schools (which surely do not care about the origins of the universe).
Besides, I bet I can think of a looong list of human beliefs once held dear by many people you'd strongly object to being taught in public schools. It's not a free speech issue, because it's paid for by taxpayers, and kids are forced to attend it.