The point is, there are no Christian laws being imposed on everyone. Every law is based on someone's idea of morality. There are many laws that allow things that are absolutely "non-Christian." But the constitution does guarantee the right for people of faith to practice said faith, just as the constitution allows you, or anyone else, to work to overturn those laws that you deem "Christian" or what have you.
That's the beauty of our constitution.
Now, I will grant you that our nation's original moral underpinning was that of Judaeo-Christian ethics. But such was the majority of our society at the time. Time has changed, and now our moral and ethical landscape is changing to that of a secular society, which is beginning to impose it's will upon an increasingly Christian minority. It is what it is. But there are no laws that are "Christian."