Bill O’Reilly has a message every American must understand: Our country is under attack -- from within.

O’Reilly’s new book, “Culture Warrior,” boldly describes two disparate worldviews that are competing for the very soul of our nation. On one side are the “traditionalists,” those who know that America is a noble enterprise, a beacon of hope and light for the world, and who understand that our belief in God and our commitment to good has made us the greatest nation on Earth. On the other side are the secular-progressives (S-Ps), who see America as imperialistic and intrinsically evil -- and who want nothing more than to sanitize our classrooms and our public squares from the alleged poison of faith.

In an exclusive phone interview, Bill told me that the culture war in which we’re all immersed is “not a political war, but is, at its heart, a social war.” He’s right. And I believe that the battle is also a spiritual one. It transcends politics. It’s bigger than Republican vs. Democrat or conservative vs. liberal, and the stakes are significantly higher than the next election.

Please don’t mistake O’Reilly’s book as just another best-seller from a political pundit (although it is the number-one seller on many lists, and the author is a media powerhouse). “Culture Warrior” is one of those rare books with the ability to inspire the reader to embark on a life-changing mission. O’Reilly affirms the instincts and values of decent Americans, reminding us of the greatness of our country and how it is worth fighting for both at home and abroad.

We live in a defining era -- a brief period in which America’s future is at risk. Will we remain the land of the free and the home of the brave? Or will we allow the secular humanists to hog-tie our rights, and use the schools to drown our kids in their dogma, while we simultaneously succumb to the siren song of malevolence (the anthem of today’s media culture) and become just another hopeless, Godless country in the mold of Western European nations like France?

In my own book, “Home Invasion: Protecting Your Family in a Culture That’s Gone Stark Raving Mad,” I provide evidence of the cultural battle and the harm it’s doing (particularly to our children). I go on to explain how we parents can protect our own homes. But in O’Reilly’s book, he tells Americans how we can protect our country. Of course, the first step is: Know your enemy. Bill names names, and he’s ready to take the heat for exposing the enemies of freedom and decency.

Some of the names, such as the American Civil Liberties Union, will be familiar to you. But even if you’re aware of the ACLU’s agenda -- which boils down to expelling spirituality from the public square -- you’ll find eye-opening details in “Culture Warrior” about this loathsome group that fights, among other things, any mention of “under God” in the Pledge of Allegiance, then defends the “rights” of groups such as the North American Man-Boy Love Association.

O’Reilly exposes how the ACLU’s founder, Roger Baldwin, flatly admitted that “communism is the goal” and added: “I am for socialism, disarmament, and ultimately for abolishing the state itself as an instrument of violence and compulsion.” Of course, the ACLU began concealing their agenda right away, but as O’Reilly proves, nothing has really changed:

“Eighty-nine years later, the ACLU is still using Baldwin’s strategy, wrapping itself in the flag and defending the rights of the ‘folks.’ Unless, of course, the folks are Christians, Boy Scouts, parents who want to know if their underage daughters are having abortions, or concerned Americans who want sexual predators who hurt children held accountable.”

O’Reilly also pulls the curtain back on who funds the S-P movement, such as far-left multi-millionaire George Soros, who has showered hundreds of millions of dollars on American left-wing causes. Soros’ animosity toward traditional America seems endless, and he puts his money where his mouth is, making him “the prime financier of a number of operations on the Internet that consistently smear conservative and traditional Americans.”

A major example of the S-P’s anti-tradition agenda in action is the war over Christmas in the public square. (And if, like some well-meaning folks, you think this isn’t an important battle in the culture war, O’Reilly has some facts that will make you think twice.) What’s the big deal about whether it’s a school “winter concert” or a “Christmas” concert? Why should we care what the holiday is called? O’Reilly brilliantly explains:

“For the S-P agenda to succeed, religion in America must be deemphasized, just as it already has been in Western Europe and Canada, where secular-progressives have made huge gains. … [T]he American S-P generals have learned that goal number one is to secularize the American public school system in order to drive children away from religion and into the S-P camp. And what is the most wondrous display of religion worldwide? Why, Christmas, of course. Little kids seeing a manger display just might develop a curiosity about this baby Jesus person. … There is no danger of that happening with winter solstice or with a holiday tree.”

Other dangers lurk for ordinary Americans when the S-P agenda worms its way into everyday life. As O’Reilly shows, we have judges who buy into a legislative crock known as “restorative justice.” To them, no one -- even the most criminally depraved -- is really responsible for his actions. In one chilling case, ignored by the media until O’Reilly had the courage to expose it, Vermont Judge Edward Cashman had to sentence a man guilty of raping a girl repeatedly from the time she was six years old until she was 10. His sentence: a mere 60 days in jail. Why? Because Cashman buys the S-P line -- the man didn’t need “punishment,” he needed “treatment.” And many in the media elite actually defended Cashman and pummeled O’Reilly.

But that’s why America loves Bill. As he proves nightly on his number-one cable TV news show, he’s a tough but fair watchdog -- the kind of ever-vigilant eye on power that our founding fathers envisioned -- willing to take the hits to expose the lies. And we should be, too. As he told me, “You have to fight for your country. We can’t let the secular-progressives destroy us.” “Culture Warrior” will provide you with a rude but necessary awakening, arm you with facts, and inspire you to become a warrior, too.