But you saying there is no science in creationism makes it true?
Now I am gathering that you are only talking about a specific brand (for lack of a better term) or theory of creationism and that you are not meaning to direct this at all possibilities and theories. If this is the case, I can get behind that.
Separation of church and state is tricky. The two main intents were that 1. Church does not hold power or authority over the state and 2. There is no push to advance one religion, set of beliefs over another. It does not prevent teaching about religions and the roles they play in history, society, and culture. It does not disregard the Ten Commandments because they are religious. Our beliefs play a major role in forming roles, mores, values, and relations in society. They can not be separated from our lives because they make us who we are.