Meghan Kruger is associate opinions editor for The Post.

How does one begin to dry the tears streaming down the ash-stained faces of Parisian Catholics? To be sure, Notre Dame Cathedral is a treasure for the world, for people of all nations and creeds. But it is first and foremost a Catholic church — where the sacraments have been celebrated for centuries, where the faithful labored more than a hundred years to erect a glorious monument to God. To watch this sacred space burn during Holy Week — the most solemn of the Christian liturgical year — stings all the more.

Here’s one suggestion for where Paris’s grieving faithful might turn for comfort: eastward, to Nagasaki, Japan.

Nagasaki has been the heart of Catholic Japan almost since St. Francis Xavier arrived on the island of Kyushu in 1549. By 1580, the country had an estimated 200,000 converts, many of them concentrated in the trading port that regularly welcomed their Portuguese co-religionists.

It was also Nagasaki that suffered when, in the late 16th and early 17th centuries, Japanese authorities expelled missionaries and prohibited the practice of Christianity. It was atop the city’s Nishizaka hill that 26 foreign priests and native believers were crucified as martyrs in 1597; it was in the bubbling, sulfuric volcanic springs of nearby Mount Unzen where Christians were boiled until they apostatized (or died).

And it was Nagasaki that guarded, over the following 200 years, a secret kakure, or “hidden,” Catholic community. These men and women had neither churches nor priests, celebrations nor sacraments. But they had faith. From one generation to the next, families passed down the teachings and traditions, clinging tenaciously to their religion in the midst of terrifying peril.

In 1865, after Japan had reopened itself to Westerners, it was a French missionary, Father Bernard Petitjean, who was astonished when a group of these “hidden Christians” emerged from the underground to present themselves at Oura Church near Nagasaki’s Glover Park. Petitjean and other French priests and nuns led the rebuilding of Japanese Christianity upon the foundation of the Nagasaki Catholics’ unshakable faith.

The great symbol of this rebuilding was a new Catholic cathedral in Nagasaki’s Urakami valley, where the area’s Christians were concentrated. Under the guidance of French priest Pierre-Théodore Fraineau, construction began in 1895, on the spot where, centuries earlier, Japanese authorities had forced the people to trample fumi-e — images of Christ and the Virgin Mary — as a way of ferreting out secret Christians. Brick by brick, the massive Neo-Romanesque structure took shape; 30 years later, in 1925, the belfry towers were finally completed. They housed two large Angelus bells imported from France, which rang out from the largest cathedral in Asia.

Twenty years later, on Aug. 9, 1945, the church was full of Japanese Catholics attending Mass in preparation for the Feast of the Assumption. At 11:02 a.m., only hundreds of feet away, the plutonium core of a U.S. atomic bomb known as “Fat Man” exploded. In an instant, it laid waste to Nagasaki; the cathedral was flattened, killing everyone inside. The pride of Japan’s Christians, the monument to their triumph over centuries of persecution, was a smoldering pile of rubble, swallowed by the surrounding post-atomic hellscape and tens of thousands of the dead.

One of the bomb’s survivors was a Japanese radiologist and Catholic convert named Takashi Nagai. As Nagai recounted in his memoir, he had been working at the Nagasaki Medical College Hospital at the time of the bombing. Bleeding from a head wound, he escaped the burning wreckage of the hospital and made a harrowing journey across the unrecognizable landscape. Inside the ruins of his house, he found the carbonized remains of his wife, alongside the melted rosary she had been praying when she died. Nagai had been diagnosed with leukemia earlier that year; his wife’s death meant their two young children would soon be orphans.

Tragedy that drops from the sky — in some cases literally — raises the inevitable question: Why? To Nagai, the improbable sequence of events that led Bock’s Car to drop its payload over Urakami — far from its original target — reflected the hand of God. At a requiem mass for the dead on Nov. 23, 1945, Nagai argued that the sacrifice of Nagasaki brought the war to an end and spared the suffering of millions. Instead of rage, instead of despair, the appropriate response to seemingly inexplicable horror was to forgive — and to commit to a path of redemption. “In the very depth of our grief,” he said to those assembled amid the cathedral’s remnants, “we reverently saw here something beautiful, something pure, something sublime.”

There was indeed something beautiful in store for Nagasaki’s cathedral. Digging into the debris, the faithful made a miraculous discovery: One of the French bells had survived. On Christmas Eve 1945, Nagai and other believers hung the bell from a tripod of cypress logs and rang the Angelus. As Father Paul Glynn writes in “A Song for Nagasaki,” the absence of any tall buildings made the song “all the clearer.”

Reconstruction of the cathedral began in 1959 and, in 1980, it was remodeled to match its original appearance. The scars are there — statues of saints broken and burned, chalices and monstrances melted and twisted. A stained glass panel in the new church depicts the ruination of the old. The famous “Madonna of Nagasaki” — a blackened and irradiated statue of the Virgin Mary — watches over the chapel.

A century and a half ago, France gave Nagasaki’s Catholics the structures of their resurgent faith. Today, Nagasaki can give France’s Catholics guiding inspiration. What do you do when your world goes up in flames, and the places you seek God are reduced to a smoldering ruin? Look for glimmers of grace where they can be found — and nurture hope for what remains.

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