Here’s a familiar stumbling block for passionate but fair-minded God-seekers: Most faiths claim to be the One True Way. But if you dare to doubt that, say, Lutherans or Shiite Muslims are the only people on earth to whom God is listening, what do you do?

Join a liberal sect? Sure, there will be openness, but probably not much holy mystery. Conservative religion offers spiritual intensity, but also the very exclusiveness that makes many cringe. The New Age welcomes everything, but its mix-and-match attitude often feels less authentic than immersion in an established tradition.

Then there’s Perennialism, a lesser-known tendency in religious thinking that was set in motion by an idiosyncratic French writer named René Guénon (1886–1951), developed by Frithjof Schuon (1907–98), and is fostered today by a small group of writers, philosophers, and professors of comparative religion.

On the one hand, Perennialism rejects a modern world that has slipped off the rails. Yet it also embraces all variations of Christian, Muslim, and Jewish faith, as well as Asian religions and indigenous schools of thought. Perennialists believe that all religions are part of one great religion; that all wisdom makes up a great river of truth that all modern people should return to for what the Gospels call “living water.”

At first glance, this all-inclusive belief system—also known as Traditionalism—resembles the direst sort of reactionary elitism. Guénon, a prolific writer who began as an enthusiast of the occult and later converted to Islam and Sufism, hated the modern world, and contemporary Perennialists have been no happier with it. “It is as if the world were the scene of the development of a gigantic plot to turn man away from God,” wrote Lord Northbourne (1896–1982), a noted British Perennialist. Northbourne slams modernity, calling it “progressive, humanist, rationalist, materialist, experimental, individualist, egalitarian, free-thinking, and intensely sentimental”—that is, thoroughly perverse and wrong.

The trouble with dismissing Northbourne as a right-wing crank is that he was also a pioneer in organic farming and a sensitive student of comparative religion whose books strongly influenced both sustainability pioneer E.F. Schumacher (Small Is Beautiful) and spiritual giant Thomas Merton.