If someone in 1995 had told me that in 20 years over 60 percent of the Irish electorate would vote to approve same-sex marriage, I'd have called this person a madman. Hell, two decades ago I'd have scoffed at predictions about same-sex marriage being accepted anywhere. But super-Catholic Ireland? Surely that would be the last place in the Western world to adopt such a radical reform.

And yet, it's happened. Like the legions of liberal commentators who have cheered the results, I'm pleased to see Irish gays and lesbians gain the right to marry. Yet unlike most of those commentators, I'm not content to leave it at well wishes expressed over a pint of Guinness.

This is a very big deal in the history of Christian culture and the moral evolution of Western civilization. Perhaps more than any previous milestone in the West's headlong lunge toward the complete public acceptance (and affirmation) of homosexuality, this one cries out for sober reflection on how we got here — and where we're going.

What that long view reveals is that institutional Christianity in the West has found itself in a quandary from which it may not be able to extricate itself.

At first blush, the result of the vote looks like a straightforward collapse of institutional Catholicism in Ireland. And indeed, the church there has been consumed by scandals (many of them involving sexual abuse) for much of the past generation. That has certainly contributed to the willingness of Irish voters (especially younger ones) to jab a thumb in the eye of the church by voting in favor of same-sex marriage.

But that's only a small part of the story.

Yes, as some have been arguing, gay marriage is unthinkable without the Enlightenment — and especially the culture of criticism it spawned throughout the Western world. But that's far from sufficient to explain why the gay rights movement has gained so much traction in our time. To explain that, we need to recognize that this movement (and its criticism of institutional Christianity's historic assumptions about homosexuality) is animated by a potent moral vision — and that this moral vision ultimately derives from Christianity itself.

As I suggested in a column back in February 2014, the movement for gay marriage appeals to the ideal of equality — and the ideal of equality originated with Jesus Christ, "who taught the equal dignity of all persons, and declared in the Sermon on the Mount that the last shall be first and the first shall be last, and that the meek shall inherit the earth." As I also noted, "These are among the most subversive teachings ever uttered — and … Western civilization has been working out their logic for the better part of two millennia, as political communities have applied Christ's egalitarian teachings in stricter and stricter terms."

This doesn't mean anything as crude as the view that "Christ wants gay marriage." But it does mean, as I concluded 15 months ago, that "we live in a culture in which reformers who successfully claim the mantle of equality inevitably triumph — because those who oppose equality find it impossible to gain public traction for their own side of the argument."

Equality always wins. And when it does, the victory is in a very real sense a triumph for the moral teachings of Jesus Christ, whether or not the reformers view their efforts in religious terms. No institution — not even a church founded in Christ's name— can withstand the subversive power of his message. Confronted by critics preaching equality, defenders of the institution's authority and traditions invariably end up sounding like modern-day Pharisees upholding abstract rules and ancient privileges against a gospel of love and universal dignity. It's fruitless.

All of this might sound like an unambiguous triumph for liberal Christianity over more tradition-bound forms of the faith — like, for instance, the style of Catholicism that has dominated Ireland for centuries. But it's not that simple.

As observers and critics have long pointed out, liberal Christianity tends to downplay the importance of formal worship, set liturgy, fixed traditions, and the imposition of sanctions for bad behavior. In their place, it substitutes a moral critique of existing norms and practices that is easily dispersed throughout the wider culture. That's why it's perfectly possible, and even predicable, that at a time when liberal Christian moral ideals are gaining in influence and cultural power, the actual churches that preach liberal Christianity are in steep demographic decline. (This might also explain why Pope Francis's enormously popular, non-judgmental, pastoral approach to the papacy hasn't translated into any measurable uptick in mass attendance or other forms of religious observance among Catholics.)

And therein lies institutional Christianity's catch-22. Conservative churches are in decline because they're so far out of step with the liberal Christian moralism that increasingly permeates public life in the West (and has helped pave the way for the stunningly rapid acceptance of same-sex marriage). But liberal churches are also in decline — because liberal Christian moralism has no need for religious institutions or forms at all.

There's just no winning for institutional Christianity.

This doesn't mean we're living through the end of religion. Aside from the rapid growth of Islam in Africa and the Middle East and the spread of Pentecostal and other charismatic forms of Christianity in Africa and Latin America, there's the fact that liberal Christian moralism is itself a form of faith — albeit one that is far more informal, demotic, and protean than the modes of belief that have prevailed throughout most of human history.

Does that make it hard to pin down, study, and understand? Absolutely.

Just like the life, death, and teachings of the God-man Jesus Christ himself.