Author David Horowitz said on Fox Nation's "Starnes Country" that the left-wing assault on Christianity in the public square is itself an assault on America.

Horowitz, author of the new book "Dark Agenda: The War to Destroy Christian America", said that the U.S. is a "unique and... Christian country."

He noted that he has a deeper appreciation for America's founding principles as a former left-wing "radical" who is "a Jew and an Agnostic" today.

Horowitz, chairman of the David Horowitz Freedom Center, said that Christianity is at the root of "every value and every principle that we hold dear."

He said that the American nation is chiefly a product of Protestants, who created a nation in their likeness after the 16th Century Protestant Reformation.

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"The assault comes from the left," he said. "An assault on Christianity is an assault on America."

He said that the Christian frame of reference has been deteriorating in the country for 50 years, since the "expulsion of religion" from public schools.

Horowitz said Chick Fil-A being banished from airports on the basis of the company's religious beliefs is a violation of the First Amendment. The Atlanta-based fast-food chain has faced opposition over its donations to groups that oppose same-sex marriage.

"Religious liberty is the cornerstone of our democracy and our civilization," Horowitz told Todd Starnes, adding that Ronald Reagan said it best when he warned that the United States is always one generation away from losing its freedoms.

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