The bishops of Quebec, the Canadian province which for centuries was the greatest bastion of French Catholic piety outside the motherland, have just published a booklet. It urges students of the faith to ponder the examples of six pioneering figures, four female and two male. As teachers, missionaries and founders of religious orders, the six all helped make francophone North America into a very devout place. Among the listed heroes is Jean de Brebeuf, a Jesuit from Normandy who befriended the Huron people and was killed by their foes, the Iroquois, in 1649.

The church reveres him as a saint and martyr; secular historians would agree that he was a central figure in the French colonisation of the New World. He and his successors helped to ensure that Quebec became a more pious territory than France itself, and remained so until at least the 1950s.

Today’s Quebec presents an utterly different picture. The Catholic heritage is everywhere, in street names, monuments and church buildings which have often been converted to secular use. But Catholic practice has plummeted. The province’s main metropolis, Montreal, is as non-religious a place as any in secular Europe. Marriage (even in the civil sort, let alone church weddings) has become an unusual choice among youngsters. A church spokesman estimates Mass attendance in Montreal at 2-4% of the population. In the province as a whole, just 11% say they are regular worshippers. But 75% of the province’s people still identify as Catholic.

To see what that means in microcosm, visit the picturesque chapel of Saint-Joseph-du-Lac in a quiet spot just north of Quebec City. A generation ago, people had to reserve a seat for Sunday Mass. In recent years, it was so deserted that the local municipality has had to step in and preserve the building as a venue for cultural events.

To anyone who knows historically Catholic parts of Europe, this combination of glorious past and secular present is pretty familiar. But the swing from piety to secularism in Quebec has been exceptionally sharp, perhaps because the starting point was so devout.

In some ways, Quebeckers recall the Italians in their residual attachment to Catholic labels and symbols and cheerful indifference to Catholic morals. The resentment felt by many French Canadians over the church’s perceived abuse of power would also be familiar to many in Spain. But Quebec resembles, and probably outdoes, Ireland in its abrupt shift from a traditional, rural way of life, where the church almost monopolised cultural and moral power, to an atomised, urban modern society.

In Quebec, as in Ireland, the church can with some reason claim to have been the historic protector of a culture that was hard-pressed by Anglo-Saxon Protestant hegemony. But in both places, the church at times had rather cordial relations with the hegemons, as left-wing nationalists resentfully concluded.

Quebec’s anti-clerical upheaval began earlier than Ireland’s, in the 1960s. Around that time, the Canadian province began undergoing what is known as a Quiet Revolution; the church lost its power over schools and hospitals, and the French language replaced Catholicism as the province’s badge of distinction.

But when a culture and a religion have been intertwined for centuries, the process of separating them is never simple, and perhaps never complete. As is pointed out by Brian McDonough, a church spokesman, the job of turning Quebec into a modern society where people thought and acted more freely was partly done by progressive Catholics, including members of the Dominican and Jesuit orders. And to this day, Quebec politicians who are not especially religious can be protective of the Catholic patrimony. One wing of the nationalist Parti Québécois believes that the Catholic heritage (whether in the built environment or as a topic in education) deserves kinder treatment than other faiths because of Catholicism’s role in shaping the province.

And only this week, the mayor of Montreal stepped in to insist that an art installation which Christians might find disrespectful (a cross lying on its side) should not be placed next to the premises of a religious order.

Meanwhile, the diminished Catholic church has to consider how, apart from celebrating past glories, it should use whatever remains of its power. In recent years, Quebec has produced a conservative Cardinal, Marc Ouellet, who now has a top Vatican job; it has also spawned left-of-centre Catholics who believe in the environment, succouring prisoners and refugees, and in atoning in every possible way for clerical abuses against indigenous people, for example through residential schools.

In a strange turnaround, the people in Quebec keenest on preserving Christian symbols like prominent crosses may turn out to be non-religious cultural nationalists, Meanwhile, some of those few whose remain devout are uncomfortable about the cross, ultimately a symbol of self-sacrifice, being used as a talisman of lingering cultural power.

In any case, in their efforts to restore the church’s credibility, the remaining faithful face a task almost as formidable as the missionaries of 500 years ago and they will have to use different methods.