James Ceasar reviews Sam Huntington’s Who Are We? The Challenges to America’s Identity and thinks that Huntington’s two ways (creed and culture) are both deficient. Rich Lowry also considers Huntington, and goes a bit farther off the mark by deemphasizing "creed": "Huntington sees an America gripped in a ’crisis of national identity.’ What is that identity? It is partly based on what Huntington calls The Creed, our belief in liberty, democracy, individual rights, etc. But The Creed has a particular source: America’s Anglo-Protestant culture, which includes "the English language; Christianity; religious commitment; English concepts of the rule of law, the responsibility of rulers, and the rights of individuals; and dissenting Protestant values of individualism, the work ethic, and the belief that humans have the ability and the duty to try to create heaven on earth, a ’city on the hill.’"

Well, I don’t think a mini-treatise has to be written on this, it is enough to say that Ceasar is closer to a true understanding of the matter than is Lowry. See this and this.

I prefer to talk in terms of principle and not ancestry, of the electric cord and the moral sentiment, as explained by Lincoln: "We have besides these men—descended by blood from our ancestors—among us perhaps half our people who are not descendants at all of these men, they are men who have come from Europe—German, Irish, French and Scandinavian—men that have come from Europe themselves, or whose ancestors have come hither and settled here, finding themselves our equals in all things. If they look back through this history to trace their connection with those days by blood, they find they have none, they cannot carry themselves back into that glorious epoch and make themselves feel that they are part of us, but when they look through that old Declaration of Independence they find that those old men say that ’We hold these truths to be self-evident, that all men are created equal,’ and then they feel that that moral sentiment taught in that day evidences their relation to those men, that it is the father of all moral principle in them, and that they have a right to claim it as though they were blood of the blood, and flesh of the flesh of the men who wrote that Declaration, (loud and long continued applause) and so they are.

That is the electric cord in that Declaration that links the hearts of patriotic and liberty-loving men together, that will link those patriotic hearts as long as the love of freedom exists in the minds of men throughout the world. [Applause.]" See full text of his speech
here.