The visit by Pope Francis to the Republic of Ireland was a huge moment in the history of this island.
The pontiff arrived into a country that has undergone an astonishing transformation in terms of its relationship to the Roman Catholic church.
Anyone in Northern Ireland who is remotely interested in politics and religion, even if from a strongly Biblical and unionist perspective, can hardly be uninterested in the social changes that have happened south of the border.
The upheaval might cause some unionists alarm and others joy but it cannot be a matter of indifference because tremors from the same earthquake are being felt north of the border.
The hold of all the traditional Christian churches has been dramatically loosened, with attendances down across the board (albeit with some individual congregations booming).
The Roman Catholic church is by no means the only institution in the Western world to have been rocked by a history of sexual abuse, but it is one of the worst affected organisations. Pope Francis’s visit to Ireland this weekend was dominated by the legacy of that abuse. Everywhere he went there were protests and at almost every key location where he spoke he expressed repentance and regret.
This has clearly affected church membership in the Republic, but is only one factor behind the decline. All the main churches find themselves out of step with public feeling on some contested social issues. Rome, however, wins some admiration for its firm positions despite popular feeling.
That the highest levels of unionism stayed away from such a major papal visit is puzzling, given that it was a huge event that would, as Dr Charles McMullen said, have meant much to many Catholics in Ulster.
The two leaders of the two main parties attended a much smaller Pink News event at Stormont, for example, which would also have upset traditionalists. Some people will say it was the very fact that the papal visit was of greater significance made it harder to attend but there is little doubt that staying away looked like a snub.