Nations

I often hear people talking about the UK as a Christian nation, or as other nations 'under God', it really makes me think what that means. What is a Christian nation? what does it look like? is there a Christian country?

Is it the UK a Christian country because the Queen is a Christian?
Is the US a Christian country because the president is a Christian and he has Christian spiritual advisors?
What happens if their successors are not followers of Jesus, does the nation stop being 'under God?'
Is the UK a Christian country in terms of an historical remnant of Christendom, just trying to keep things the way they were?
Or what about regionally? Is Northern Ireland more Christian? Or some of the Scottish Isles? Places which have held onto tradition, have retained who they are and are unmoving on certain issues. I read recently that there are no mosques in Northern Ireland, more Christ like? or more intolerant? Or more secure in who they are?
What about the Republic of Ireland, who this week have had huge protests about the death of a woman because she could not have an abortion in this Christian country?
What about France, one of the most secular countries on earth, who have had large protests this week against gay marriage?
What about Bhutan? Whose government believe that the peoples happiness is more important than their wealth?
What about Uruguay? Whose socialist leader, only takes a wage the equivelant to that of an average worker and gives the rest to charity and lives on his wife's farm rather than the official residence.

How are we known?
I suppose it is the same as personally?