Alright, let me explain it. Establishment clause of US means that the government may not establish a religion - that means in actuality or in effect. This means the US government is neutral. However, on the other hand the people have the absolute right to freedom of religion as well as freedom from religion - you have the absolute right to believe whatever you want and not be subjected to others views - thus religious symbols and teachings are not necessarily forbidden, they just have to follow certain guidelines that don't establish religion by the government. For example, the government establishes a religion if it only allows a Christian nativity scene and not other holidays to be represented at the court house - the ten commandments may be taught in school but only as an early form of a legal system, not as a religious fact - government may not send public money to subsidize and fund private schools (religious usually), however they can give the people money for school and if they choose to spend that at a religious school it's their choice, the government has established no religion, they've just subsidized education.