Sometimes the old gods slowly fade into oblivion. Contrary to popular perception this seems likely the case for ancient paganism. The conversion of Constantine to the Christian religion began the process of a hand-off and the commanding heights of classical culture that took over a century to complete. There were punctuating moments, such as the apostasy of Justinian in the 360s, or the mostly symbolic ban on public paganism by Theodosius in the 390s (the Serapeum was destroyed by a vigilante mob). But pagans in the form of the Neoplatonic school persisted into the 6th century, while elite pagans such as Marcellinus maintained power and influence deep into the second half of the 5th century.
Call this “normal” cultural evolution. Antiquity evolved from being predominantly pagan to predominantly Christian (though a small cultured pagan minority persisted even until the Islamic conquest in the Near East, such as the Sabians of Haran).
The Reformation period was different. In a single generation one thousand years of a coherent and unified Western Christian ideology collapsed, and was replaced by something very different.
Note here that I said Western Christian ideology. The reality is that Western Christianity was never as unified or coherent as Western Christians themselves envisaged themselves to be (or aspired to be). There were episodes of hostility between particular kingdoms and the Roman papacy. Heresies such as that of the Cathars, and popular revolts with a religious tinge such as that of the Hussites. And finally, there were periods of multiple popes, which undermined the credibility of the institution of the Church in the medieval period.
But all this pales next to the magnitude and scope of the revolt against the establishment of the Western Christian church that occurred in the 1520s. Martin Luther went from being a Christian cleric within the established Church to declaring the pope the anti-Christian! Previously devout peasants in Switzerland turned on the relics and churches which they had only recently venerated, and engaged in mob iconoclasm. Whereas monarchs, such as Henry IV, ultimately compromised with the clerical estate (or, submitted), Henry VIII of England managed to destroy or subordinate the institutions of the church to his own will and pleasure.
There are many theories for why the Reformation occurred when it did. Some of them are rooted in technology, in particular the printing press. Others point to the development of proto-national identities, such as the rise of German nationalism and its leveraging by Luther against his “Roman” persecutors.
These specific issues are not interesting to me. Rather, what they point out to us that there can be cultural revolutions that occur very rapidly. One can point to the pacific post-World War II Japanese, and contrast them with the militaristic Japanese of the first half of the 20th century. Or the shift of Russia from being a conservative autocracy in the 1910s to a revolutionary society in the 1920s. But these are modern events, and moderns are liable to suggest that our own epoch is sui generis in these sorts of turnovers of values. But the Reformation shows that revolutionary changes in whole societies can occur rather rapidly even in a pre-modern context.
In other words, cultural revolution is not a derived characteristic of our species, but perhaps a very old one. The rapid expansion of the Austronesians. Or the radiation of non-African humanity. These come out of a vacuum, a cultural-demographic analog to the inflationary universe. But given enough time perhaps our species is simply subject to these sorts of explosions of creative change and innovation.