Jonathan Sandys has written a new book about his great-grandfather Winston Churchill’s role in and attitude toward Divine Providence. Sandys doesn’t try to explain or exaggerate Churchill’s opaque religious beliefs. Instead he explains that his ancestor’s career was animated by an attachment to what Churchill called “Christian civilization,” which he defended both against Nazi paganism and, in his Iron Curtain speech, against Soviet oppression.

By Christian civilization Churchill meant a Western society shaped by biblical ethics premised on human dignity. It included the protection of individual rights against the state and a broad legal equality for all persons, including free speech and religious liberty. Even by the 1940s Europe was not overwhelmingly pious, nor was Churchill himself much of the time. Yet he was consistent in assuming that the code of behavior flowing from Mount Sinai and the Sermon on the Mount had created an ongoing view of humanity more decent, humane and enduring than any alternatives.

Of course it’s no longer common to speak of Christian civilization. Secularists pretend that religious faith had no role in creating what even they cherish about wealthy, modern free societies. And many Christians in their current funk placidly assume they live in a post-Christian era without understanding that Western secularism itself is a sort of byproduct of Christianity.

But even if the churches of Europe are mostly empty, and even if secularism governs elite culture in America, the West’s political and cultural particularities are still irretrievably Christian at their core. Societies where law is no respecter of persons and not the tool of personal whim for rulers are still shaped by a Christian-influenced transcendent authority.

Can the lawful polities that descend from Christian civilization long endure absent vibrant religious faith among their people? Can such polities superimpose over explicitly non-Christian societies? Or can these polities survive an influx of new population shaped by very different assumptions outside Christian civilization?

The last question relates to recent mass migration of mostly young men, overwhelmingly Muslim, from the Middle East, North Africa and Central Asia. Hungary’s semi-authoritarian premier, with support from a Catholic prelate in his country, is laboring to keep Mideast Muslim migrants out, purportedly in defense of Christian civilization. The Orthodox Church in Bulgaria has similarly spoken against accepting large numbers of Muslim migrants lest their nation’s historically Christian culture be diluted lost.

Christian historian Philip Jenkins, previously skeptical of concerns about Europe’s Islamization, has recently become more alarmed about a potential “cultural and social revolution.” Meanwhile, Mideast Christian refugees, who are specifically persecuted for their faith, and even tormented by other Mideast migrants at camps in Europe, receive almost no specific assistance from Western governments. German police unions have urged segregating migrants by religion after the reported near lynching of an Afghan Christian in Germany by Muslim fellow migrants.

It’s a virtue of Christian-shaped societies that migrants and refugees are often offered sanctuary. Where all are equal before the law, there can’t be legal preferences based on religion. And historically, many migrants from non-Christian societies have successfully integrated into the Christian West, adopting its mores, and even helping to export and globalize those mores.

But Christian civilization has endured because it is not mindlessly idealistic but understands the limits of human nature. Can European liberties based on Christian notions about legal equality for all persevere if challenged by millions of new migrants who insist on a very different civilizational outlook? What if large chunks of the future Europe, and perhaps even America, reject legal equality for all and aggressively assert different legal treatments based on religion, gender or other considerations?

Christian civilization has often survived and thrived alongside its own internal critique by adversarial voices, but not always. The two great totalitarianisms that Churchill resisted were implosions of Christian society. Nazism deified and perverted Christianity’s scientific and technological achievements. Bolshevism tried to impose human equality, a Christian idea, by brutally banishing private property and all individual liberty. The result was a perversion of equality. Tens of millions died from these two heresies against Christian civilization, both facilitated by the social collapse of real Christian faith and ethics.

Currently Christian civilization faces different perils. Each is potentially a betrayal of its own identity, by either mass acceptance of or mass rejection of millions of Muslim migrants. Churchill’s legacy offers no explicit counsel on this issue. But he was certain that cultures fed by the Ten Commandments and Sermon on the Mount have unique virtues meriting vigorous defense. Whatever policies we ultimately pursue, our culture, which emerged from vibrant Christian soil, cannot survive by denying what it is and whence it came.