Faith and common sense together made the founders' soaring vision of political liberty possible. When we understand that, many things otherwise obscure are brought into sharp focus.

In On Two Wings: Humble Faith and Common Sense at the American Founding, Michael Novak wrote: "The founding generation moved easily between faith and practical, common-sense reasoning, indeed mounted upwards on both those wings in unison." Novak got it just right. If we seek to understand the founders and their generation, we need to navigate by using Novak's profound insight as our guiding star.

For one example, it helps us understand the long war on the American Idea by Americans who reject the American Idea.

The Civil War is a good place to start. In that bloody struggle, Americans who rejected the founders' vision banded together to use military force against the government the founders had created. Alexander Stephens, the vice president of the Confederacy, in his famous Cornerstone Speech, was perfectly clear about the Confederates' rejection of the founders' idea of America:

The corner stone of our new government rests upon the great truth that the negro is not equal to the white man; that slavery, subordination to the superior race, is his natural and normal condition. Our new government is the first in the history of the world based upon this great physical, philosophical, and moral truth.

Union victory did not put an end to the war on the American Idea by Americans. Those who continued the fight simply adopted a different strategy.

Direct military attack had failed. Consequently, what was needed was a long war directed at the foundations of the American Idea, faith and common sense.

The first target was faith. Although the two sides in the Civil War were fiercely divided over politics, they were united in their faith. As Lincoln said in his Second Inaugural, both sides "read the same Bible and pray to the same God." Lincoln was not paying lip service to a political piety. America in his time was a deeply religious nation. Even the Americans who rejected the founders' vision for America attended church and tried to find justifications for their politics in the Bible.

How has the war on faith gone? The question answers itself. Prayer has been pushed out of the schools, and religion, except for Islam, is being pushed out of the public square. Even Christmas, except as a commercial extravaganza, is under attack.

It is interesting to note that Americans who attend church and read the Bible are generally patriots, while those who do not often are not. That tells us that the American opponents of the American Idea know what they are doing. They have chosen their targets well, and they have scored important victories in their long war on America.

With faith on the ropes, America's American opponents have more recently opened up a new front in the war by attacking common sense. That campaign is also going well – so well that it is now impossible to count all the ways. Surely, it is plain common sense that the first job of the federal government is defending America's borders. Yet the government that won the Civil War is now so securely in the hands of its domestic enemies that it cannot do even that.

Where else has simple common sense been tossed out the window? You name it. How about the simple fact that humans are either male or female? Not long ago, a boy in a tutu and a tiara who claimed he was a girl would still be a boy. Today, academic, government, and cultural elites tell us there are many genders; one site reached just now by Google tells me there are 63. Those same elites tell us we had better get with the many-gender program, or else. And while we are at it, we had better get politically correct about marriage. Marriage, we are told, is no longer about uniting one man and one woman in a union blessed by faith and common sense.

Political correctness is quite simply the war on common sense. It is a war by the elites on the common people and on our shared understanding that has made it possible for us to rule ourselves under the Constitution.

Once our common sense understanding of the basic facts of life is sufficiently overthrown, it is mission accomplished for the Americans who reject the American Idea. With faith also on the ropes or perhaps even down for the count, tossing aside the Constitution then becomes a mere detail, to be done without even firing a shot.

Robert Curry serves on the Board of Directors of the Claremont Institute and is the author of Common Sense Nation: Unlocking the Forgotten Power of the American Idea from Encounter Books. You can preview the book here.