|The word "nation" is ambiguous. Does it refer to a body of people, or does it refer to a government or political institution?
There is a difference between "the State" and a "society."
People can think of themselves as being a part of a society without being a part of any "government" that claims jurisdiction over that society.
Every human society should be based on the Christian religion and follow Christian morality.
Article III of the Northwest Ordinance requires:
Religion, morality, and knowledge being necessary to good government and the happiness of mankind, schools and the means of education shall forever be encouraged. 
In his Farewell Address, George Washington, "the Father of his Country," reminded the nation:
Of all the dispositions and habits, which lead to political prosperity, Religion, and Morality are indispensable supports.—In vain would that man claim the tribute of Patriotism, who should labor to subvert these great pillars of human happiness, these firmest props of the duties of Men and Citizens. —The mere Politician, equally with the pious man, ought to respect and to cherish them.—A volume could not trace all their connexions with private and public felicity.—Let it simply be asked where is the security for property, for reputation, for life, if the sense of religious obligation desert the oaths, which are the instruments of investigation in Courts of Justice? And let us with caution indulge the supposition, that morality can be maintained without religion.—Whatever may be conceded to the influence of refined education on
minds of peculiar structure—reason and experience both forbid us to expect, that national morality can prevail in exclusion of religious principle.—
When we fail to adhere to Christian morality, we must repent -- as a nation. John Adams:
- "giving to it the character of a national act:"
- it is also most reasonable in itself that men who are made capable of social acts and relations, who owe their improvements to the social state, and who derive their enjoyments from it, should, as a society, make their acknowledgments of dependence and obligation to Him
Every Society should be a covenanted Christian society:
The Duty of Social Covenanting