There were indeed Puritans who claimed that America had a special place in God's providence. Some even described America as the "new Israel" led from slavery into the promised land. There is a natural temptation for such attitudes to devolve into the suggestion of divine approval for a country's actions right or wrong. Linker suggests that we should blame Calvin for this “theological self-confidence” among Americans that borders on “over-confidence.” Sadly, I don't find anything in Calvin's teaching that suggests that he would approve of associating an earthly realm with the Kingdom of God.
Calvin, who described the heart as an idol factory, would understand someone who turns a nation or an ideology into a god. Moreover, he would call it a sin.