Progressive Christianity? You’re kidding, right? Christianity is, has always been and will always be progressive. “Progressive Christianity” is redundant.

On the second Sunday of Advent last December, I found myself in the Anglican Cathedral Church of St. James in Toronto. The scripture reading for the day reminded me that Christianity’s revolutionary message began even before the birth of Christ, with the ancient Jewish prophets. In the reading, Isaiah (11:9) foretells the coming of the Prince of Peace, when “they will not hurt or destroy on all my holy mountain; for the earth will be full of the knowledge of the Lord as the waters cover the sea.”

Christianity was undoubtedly revolutionary at its birth. As the 20th-century poet W.H. Auden noted, “A faith which [holds] that the Son of God was born in a manger, associated himself with persons of humble station . . . yet did this to redeem all . . . required a completely new way of looking at human beings; if all are children of God and capable of salvation, then all . . . merit the serious attention of the poet, the novelist, and the historian.”

And Christianity is progressive in every age. St. James Cathedral is almost overwhelmingly lovely: a vaulted, light-filled Victorian artifact of a church, imbued with aspirational holiness. The epitome of a conservative Christianity of a bygone era, one might say.

But look closer, and see the congregation. Beside me sits a quietly gracious woman of Asian origin. In an adjacent pew, a slim brunette lifts a superb soprano in tune with her metrosexual companion’s rich tenor. The young black Canadian reading so mellifluously from Isaiah retains a slight inflection suggestive of a childhood spent somewhere other than Toronto’s bleak mid-winter. The aged and the infant; the bold and the broken: we are all part of the family. “One bread, one body, one Lord of all,” to quote John B. Foley’s hymn (based on 1 Corinthians 10:17).

And yet, what loudly self-describes as “progressive Christianity” in our own time is generally but reductionism or agnosticism.

Reductionism is nothing new. From Thomas Jefferson’s elimination of the “supernatural” in his 19th-century edition of the Bible, to the 20th century’s distaste for wrestling with nuance and metaphor, to the Jesus Seminar’s voting on the genuine words of Jesus, reductionism reduces the rich brew of the scriptures to skim milk.

As to agnosticism, the greatest enemy of faith is blind certainty. Every Christian ought to be just a little agnostic: not knowing — while practising informed hope — is the essence of faith. After all, is Christianity largely mythic? St. Jerome noted that in the fifth century. Ought the Bible to be read critically? That’s so 1860s. Can we really know the historical Jesus? Albert Schweitzer thought not in his 1906 book The Quest of the Historical Jesus. How about sexual orientation? In last year’s Epiphany,author and Observer columnist Michael Coren found that the inclusive United Church got it biblically right.

Some charge that contemporary “progressive” Christianity goes “too far” in its biblical and theological critique. It doesn’t go too far. In fact, it doesn’t go anywhere. It offers nothing new while turning down the volume of the prophets’ thunder and watering down the wine of God’s love.

“Mere” Christianity, as C.S. Lewis described the essential faith, is always progressive — and it’s dangerous. It’s about following Jesus. Rev. Daniel Berrigan, a Jesuit priest and activist who died last April, understood that: “If you want to follow Jesus,” he said, “you better look good on wood.”

This story first appeared in the March 2017 issue of The Observer with the title “Conundrums: What is progressive Christianity?”