I know more about Christianity than Judaism, but I see post-Second Temple Judaism as split largely between the orthodox traditionalists and the potential for reformed pragmatists/secularists. The question is how to be the best kind of Jew without the Temple. And I’ve written on how monotheism functions as biting satire since Jewish righteousness implicitly criticizes all idols and vanities (links below). That’s the upshot of saying there’s only one God and that this God is immaterial and different from all incarnations or “graven images.”
Thus, Judaism has always had the potential to be secularized and modernized, as shown in the skepticism of Job and Ecclesiastes, and as Jack Miles explains in God: A Biography. The character of God changes drastically over the course of the Tanakh, until God is practically irrelevant in Song of Songs, Ruth, Lamentations, and Daniel. What Jews learn implicitly from their sufferings is that God is silent and perhaps has lost interest in his chosen people, so they had better learn to take care of themselves. That’s the secular humanism made manifest in Reform Judaism.
Orthodox Jews carry on the traditions to honour their ancestral ties as much as to honour God (who couldn’t reasonably be expected to care about the minutiae of those rituals and tribal prejudices). The point is to preserve the Jewish social identity so as not to let all that historic suffering—especially now the Holocaust—go to waste.
Christianity has also all along been implicitly secular because of its ties to the Roman Empire and because of its incoherence which is meant to test and increase the flock’s faith for totalitarian purposes. The Church’s authority is supposed to make obsolete not just Jewish righteousness but all countercultural social critiques, including Jesus’s. All that matters, according to the Pauline portion of the New Testament is faith in a once-and-for-all human sacrifice, and in the institution that rose to protect that message.
The Christian flock confines its thinking to the exoteric insistence on that preposterous faith, while the Christian elites considered themselves free to indulge in “heresies” and in incorporating Greco-Roman philosophies. They were often persecuted by the Church, of course, but the Christian intellectual elites recognized that Christianity is a holding pattern, a stasis meant to hold Europe together after Rome’s collapse. The flock were content with the medieval simplicities, but there were always heretics who sought progress and societal rebirth.
The notion, then, that modern secularism originates in theistic religion is only trivially true, as far as I can see. The point is that those religions overcame themselves, as their secular potential was manifested in the modern revolutions (in the Renaissance, the Protestant Reformation, the Scientific Revolution, and so on).
What you’re calling Christian “universalism” (or Catholicism) looks like a euphemism for totalitarianism. Sure, though, this clashed with Jewish nationalism, pragmatism, and satirical skepticism. Both religions have been implicitly secular and self-overcoming, but Jews were less deranged by that upshot of monotheism. Jews accepted that we must improve the world ourselves because God is beyond nature, and he does what he likes and can’t really be trusted to keep his promises the way we’d like. He preserved Jews but also tormented them over the centuries to teach them a lesson about the necessity of certain moral standards.
Christians, by contrast, lapsed into self-deception. The Church couldn’t afford to free the minds of Christians because of the social risks after the collapse of the Roman Empire, and because the Church leaders became corrupted by their power and by the absoluteness of their creed. Humanistic pride and the pursuit of progress and happiness became cardinal sins, for Christianity.
Modernity was thus more disastrous for Christianity than for Judaism. True, Protestantism especially made its peace with capitalism, but only by further nullifying the Christian message as a practicable aid. The Church lost its power in the West via the democratic overthrows of the monarchic regimes. And all forms of Christianity still sit uneasily with liberal, progressive values. Islam, meanwhile, combined the worst of both religions (the sanctimony, humourlessness, and conservatism), and still hasn’t reckoned much with modernity.
Again, what’s offensive here, then, is mainly an aesthetic and ethical failing. Sanctimonious monotheists who rail against secular progress don’t understand the satirical point of the prophetic critiques and visions. The “universalism” is just an excuse for an elite’s “conservative” (patriarchal, totalitarian) control over the broader population via glorified dominance hierarchies. This totalitarian conservatism clashes not just with Jewish nationalism and self-absorption but with Greco-Roman humanism and with the seeds of secular humanism within the monotheistic religions.
