I think we have certainly been (in the past) a country which though of itself as Christian, in that there was only one religion in the country (with the exception of a few Jews & Gypsies), and everyone who adhered to any religion adhered to that one,and the government was made up of people who at least claimed to be following the Christian religion. Whether the acts performed in the name of that religion were always what we would now consider to be Christian is another matter!