This week, New York Post columnist Ryan Sager, one of the most thoughtful young conservatives writing today, publishes an important new book, "The Elephant in the Room: Evangelicals, Libertarians, and the Battle to Control the Republican Party."

The gist of the book is that the coalition of religious conservatives and libertarian free-marketeers is breaking apart. The basic principle that held them together throughout the postwar era -- the idea that morality and virtue need to be freely chosen to have meaning -- is breaking down. The traditionalists have gotten the upper hand and increasingly reject the idea of freedom when it comes to things like gay marriage, pornography, drugs and abortion.

The traditionalists, infused by evangelical religious fervor, have taken that wing of the party far beyond its historical roots. In the past, traditionalists were religious and pro-religion, but highly tolerant of those non-religious conservatives who derived their ideology from natural law or free-market economic principles. Thus traditionalists like William F. Buckley and Russell Kirk could coexist with atheists like Ayn Rand and Ludwig von Mises. They respected each other's views even if they disagreed with their foundation.

The traditionalist-libertarian coalition was also a political marriage of convenience. Neither group commanded sufficient votes to defeat the liberals, who were dominant from the 1930s to the 1970s. Since liberalism was abhorrent to both groups, they were able to make common cause.

Traditionalists hated the militant secularism of the liberals, who sought to banish religion from the public square, and their scorn for traditional values and ways of doing things, whether in the schools, the churches, the culture or within the family itself. The 1960s were a watershed when liberalism expanded far beyond economics, where it was largely confined during the Roosevelt era, to embrace feminism, drugs, and free love, combined with utter disdain for order and the institutions that sustained it.

So extreme was the revolt against tradition in the 1960s that many New Deal liberals believed the New Left was threatening to bring down civilization itself in an orgy of nihilism. Feeling they had been mugged by reality, a number ended up switching sides, becoming neoconservatives.

Meanwhile, the libertarians were empowered by the collapse of Keynesian economics in the 1970s. John Maynard Keynes had argued that government deficits were stimulative. When this idea appeared to work during World War II, the old balanced-budget constraint was abandoned. This opened the door to a vast increase in government spending, which reached a pinnacle during Lyndon Johnson's Great Society.

But when inflation became a serious problem in the 1970s, the Keynesians really had no good explanation for it or a cure. In this intellectual vacuum, libertarian economists like Milton Friedman gained credibility and influence by arguing that tight money was needed to stop inflation. Continued...