This is a very important concept. Some fundamentalists on the right seem to think "religious freedom" means the right to impose their own religion on their fellow citizens, even if they have to do it with legislation. It does not. Religious freedom means the government will not favor any religion over any other religion, regardless of what religion may be dominant in this country. It also means the government will not require any American to believe in a religion at all -- thus protecting the right to not be religious.
Americans have the right to believe or not believe in religion, any religion, but they do not have the right to use the government to force their particular religion on anyone else -- and that means government at any level (local, state, or federal).