Someone at Vox’s asked when Catholic bishops started meddling in US politics, whether it began with JFK or predated him. It’s really both. Of course, there’s a long history of the Church being involved in politics (and vice versa). After all, for centuries the Church guided the Holy Roman Empire, and at one time the Vatican ruled over the Papal States and was a military and political force in its own right. Compared to those times, the Church’s direct influence on politics today is quite low.
The difference now is that the Church’s influence on politics is almost entirely in the service of economic and cultural Marxism. While there are orthodox, traditional bishops (and more of them now thanks to Pope Benedict), they spend most of their efforts trying to shape up their own flocks. Some of them do speak out strongly against sins like abortion and homogamy, but they do that officially from the pulpit. They don’t pal around with politicians and try to influence them personally, because that’s not their job, and they have plenty of problems within the Church to work on. So when it comes to playing politics, the leftist bishops and priests pretty much have an open field.
So when did it start? I’d say there were two main events. The first was the Soviet infiltration of the Church. The USSR attempted, often successfully, to infiltrate many influential organizations, of course: governments, Hollywood, universities, etc. But the Catholic Church — on record as one of the most outspoken and influential opponents of socialism — was a major target. Soviet agents worked to place thousands of men in seminaries, some outright agents and some simply sympathetic to Marxist ideals. Many of these men were ordained and rose into positions of influence, ready for the next blow.
Which blow came in the form of Vatican II. The context of Vatican II was that the Church was doing very well — vocations were up, the pews were full — but some thought things were getting a little stale and old-fashioned. So the idea was to throw open the windows and let in new ideas, while at the same time opening up the Church in a more welcoming way to non-Catholics. In hindsight, it was a staggering show of hubris, as they seemed to forget that when you throw open the windows, bad can come in with the good. By convening a Council, everything that wasn’t a matter of settled doctrine could be changed, and even settled doctrine could be obfuscated and interpreted in confusing new ways. The leftists within the Church took full advantage of this opening.
Church members who wished the Church could change her stance on things like socialism, artificial contraception, or divorce simply acted as if she had. The attitude developed that Vatican II had made virtually all doctrines optional and subject to personal interpretation and approval. That allowed priests and bishops to preach virtually anything they wanted, and only a few hide-bound traditionalists would object.
There were other factors, of course. Modernism had been a growing problem for a long time — just ask Chesterton — but the Soviet infiltration was the first concerted effort by a major power in that direction. And to some extent, all institutions were affected; the Church wasn’t and isn’t alone in swinging toward leftism, globalism, socialism, equalitarianism, and so on. But the Church does seem to have been especially affected — the institution feared for Crusades and Inquisitions becoming a doormat for nearly every left-wing cause — and I think the double-whammy of Communist infiltrators and Vatican II accounts for that.
The good news is that the generation that was infiltrated is on the way out. The seminaries have been considerably cleaned up, thanks to the homosexual abuse scandals (which were part of the infiltration, not a separate issue), so younger priests are much more orthodox. They just can’t be too open about that, lest it get them in trouble with their Boomer superiors. And in Pope Francis, who hails from the part of the world afflicted with LIberation Theology (Marxism with a Catholic coating), we have an instructive example of what lies in that direction.
In 1884, Pope Leo XIII had a vision in which he saw a Job-like conversation between God and Satan. The exact conversation isn’t known, but the gist was that Satan claimed that he could destroy the Church if God gave him a century and more power over those who would follow him. God consented, and Satan chose the 20th century, or the period running approximately 1885-1985. The 70s and 80s really were the nadir, with the effects of Vatican II, the Novus Ordo, and the abuse scandals. Since then things have been improving, but slowly. Much damage was done, and many feet are still being dragged, so we have a long way to go.