what is a Christian country? What does it entail, what are the boundaries of that.
At a minimum, it would be a government that acknowledges the Christian God, even if not accepting an official denomination.
You go somewhere like Mexico, and the Church is everywhere, and public officials are openly and intrinsically Christian and realizes that Christmas is the celebration of the virgin birth, not a week off to celebrate Santa Claus and Hanukkah and Festivus.
A place where faith and religion isn't banned, but the opposite--it is an inseperable part of what government does, and its policies and rules are meant to back up Christian principles.
By that measure, even European nations with low churchgoers, would count. At least the government is operating under Christian faith and principles--it's up to the people to accept or reject that based on God's given free will.
1) Is this part of a move to undermine so-called right-wingers' loyalty to the Constitution - specifically to free speech and guns.
The constitution is merely the rulebook that outlines what spheres our different bodies of government can and cannot regulate, and how they can lawfully do so. Every country has a rulebook for its government to play by. There are things I like and dislike about our governments rulebook, but I don't feel that I owe any allegience or loyalty to it. It's just the rules our rulers must play by (when they pay attention to them, which they often do not).
As to the OP's question, most of the founders who wrote the laws did believe in God, though to varying degrees of what we would recognize as Christianity. But whatever their personal faith was, they created a government that was secular. Can you imagine a bill of rights that does not mention God at all?
Dr. Kevin McDonald calls America the Great Shopping Mall, and it was certainly set up with that sort of end goal, as opposed to creating a safe and stable society that operates under God's law and encourages those to live a holy and spiritual life.
What's most important under American Federal Law? Life, liberty, and the pursuit of happiness.
Life can be expressed as the fear of dying. Those who have God's salvation do not need fear death.
Liberty is freedom or lack of restraint, licentiousness, and sin. Unless something is deemed unpopular by majority rule democracy, it is allowed.
P of H is commonly translated as property. In other words wealth or mammon.
Do you see how this is not at all a recipe for Godliness?