Seperation of Church and State should happen. Unfortunely, Christianity is the background behind the United States and will remain strong, even if many people don't believe it. The money will still be plastered with words about trusting something that merely doesn't exist, and people will still wear crosses to work and such. Seperation of C&S can't be too extreme to stop people from showing their own beliefs, cause they have rights to do so, and thus, people will still find ways to keep it in the state.
I don't think it should be as extreme as to stop people from expressing themselves freely and to not surpress their rights, but some things shouldn't be based on Christianity, because America is a country for all sorts of people to come. And that means multiple religions. And I am sure it's partially insulting (Or they ignore it) that some of the government things have Christian beliefs etched into them. They've been re-modeling money and they could have taken those parts out, but they don't. While I know Christianity is the background of America, people change and countries change. And sometimes, changes are to make everyone happy.
...I have no idea if I make sense. I can't word my thoughts out well.