In Saudi Arabia and Iran, everybody is required to live as a Muslim. I see no reason why we shouldn't do the same thing in America, which is a Christian nation established by Christians, for Christians. As a Christian nation, we can (and should) require everybody to live as a Christian -- or at least offer a higher class of citizenship to Christians. People who do not want to abide by established Christian beliefs and norms are free to live elsewhere.
It should be self-evident to any Christian what a Christian is supposed to believe and how a Christian is supposed to live. As an atheist, you would not know this -- but it still does not relieve you of the responsibility of living like a Christian if you are going to CHOOSE to live in a Christian society.