“In the ’40s and ’50s, people replaced the colonialism of the Brits with a kind of colonialism of the church,” said Aodhan O Riordain, a senator from the Labor Party. That fostered an intermingling of Catholicism and Irish identity that was “a toxic mix,” he added.

For decades, legislation opposed by the church was doomed to fail. Eamon de Valera, an ardent Catholic who served as president or prime minister several times between 1921 and 1973, enjoyed a close relationship with the archbishop of Dublin, John Charles McQuaid, who helped steer Ireland’s religious life for three decades and made assertive policy suggestions.

“The Catholic Church’s hold on the state, the ways in which it sought to influence the state, remained strong for a very long time,” said Ms. Smyth. “For much longer than you might have thought possible.”

Even in its diminished state, the church continues to play a role. It controls almost all state-funded primary schools — nearly 97 percent — and the law allows them to consider religion as a factor in admissions. Many hospitals, too, are either owned by the church or located on church property.

But Diarmuid Martin, the current archbishop of Dublin, said the church “certainly” enjoyed less influence now than in the past. He blamed the one-two punch of broad social trends and the abuse scandal for the church’s declining fortunes.

“The scandals emerged at a moment which was either just the wrong time or the right time, depending on which side you are, for them to emerge,” the archbishop said. “The two things, the change in the attitude to the church and the abuse, came together and had a disastrous effect.”

‘My God, I Can’t Get an Abortion Here’

Those changing attitudes were driven by epochal economic and technological shifts felt in all countries, like the expansion of free trade and the birth of the internet. But in Ireland, the old order had largely managed to adapt.