The link below is to a PDF of an old article written in the 1940’s (hence the slightly antiquated language) by Francis D. Nichol, the long-time editor of an Adventist periodical, the Review & Herald.  He was responding to the argument of the National Reform Movement (a group of American Christians pushing for a National Sunday Law in America) who proclaimed that America was a Christian nation and that therefore its laws must be “Christian.” Read his response here (it may take a few minutes to download): Is America a Christian Nation? – Francis D. Nichol