The thing is, creationism is a biblical myth. A complete and utter fabrication by people who had no idea where rain came from or why the sun rose everyday. They had no idea how the earth was formed and certainly little conception of how the earth relates to the solar system and Milky Way. It is no different from the other myths created by people to try to explain the world around them (Greek and Mayan myths come to mind). I really think the majority of Christians know that the world wasn't created in six days by god, but that the story was used to try to explain the world as these people knew it then.
But, regardless of whether you think the earth is 6000 years old or 4.3 billion years old, surely we can all agree that creationism and religion has absolutely no place in any public science classroom. Just like we don't teach kids the Mayan myth about creation, we shouldn't teach any other religious myths about how the world formed. We should teach the science about how the earth was formed. We have plenty of scientific evidence to form a scientific theory about how and when the earth formed. We have replaced myth with science. The more we can replace myth with fact, the better off we'll be.