The Catholic Church isn't quite as bright and shiny as it used to be. If it's losing ground in Ireland, this is remarkable.

Your link doesn't prove anything about what Catholic theologians believe.

I'm not sure that Catholics actually tithe, even though they're supposed to. Does anyone have information?

More generally, trying to build irrational loyalty may have non-obvious costs.

As for rational loyalty, a while ago, I went to a workshop hosted by Unitarians about the people's long term relationship with their religion. The thing that struck me was the amount of mutual aid within religions. This is something which can build stable social structures, though I grant that there's got to be felt unity to get the mutual aid started, and you may be right that meeting is essential to make that happen.