The first post in this series_ discussed the achievements of the Roman Empire in the 1st-2nd centuries. The second post covered changes in the late 2nd to 4th c. AD. This post is available as a video at https://youtu.be/pwtMDqTZeVk.
4. Philosophy & religion during the 3rd-4th centuries
4.1 Constantine’s conversion
Emperor Constantine (ruled 306-337) saw religion as a possible way to secure the allegiance of the army and the people without relying on brute force. He converted to Christianity in 312. Many intellectuals and administrative officials promptly followed his lead. At the end of the 4th c., Christianity was made the official religion of the Empire, although by that time, Christians were still only about 10% of the population.

Constantine’s conversion to the Christian religion came at a time when religious feeling among subjects of the Empire had been building steadily for centuries.
4.2 Intellectuals and upper classes
Among philosophers, intellectuals, and the upper classes of the 1st-2nd c., Stoicism had been the most popular philosophy. Its adherents believed that happiness comes from performing one’s duty to a larger whole. The last famous proponent of Stoicism was Emperor Marcus Aurelius (ruled 161-180). By the 3rd c., Stoicism had been largely displaced by Neoplatonism and Neopythagoreanism. Both combined religion with philosophy.

Plotinus (d. 270), the leading Neoplatonist, was a favorite at the court of Emperor Gallienus (of the 5% silver wash on coins: see §3.4 in last week’s post). Plotinus emphasized selected parts of Plato’s writings:
- One can only reach the superior reality of the transcendent Forms via mystical experience.
- No really important ideas can be transmitted conceptually: reason is impotent.
- The most important world is not this one, but another, superior one.
Neopythagoreanism adopted some tenets of Platonism, adding the desire of the soul for mystical union with the divine.
This is what passes for philosophy at this point.
4.3 Lower classes, including soldiers
The lower classes in the Empire were never educated in a rational philosophy. They always relied on religion for their moral code.
In the late Empire, the army was being recruited from the barbarians who had never had any exposure to rational thought as developed by the Greeks. Soldiers practiced many different religions, but all shared an emphasis on faith, salvation, immortality, and a messiah. Giving a man something new to believe in is easier than teaching him a new way to think … so the troops didn’t object to Constantine’s appeal to religion.

4.4 Why Christianity?
Christianity shared with many other Eastern religions the belief in faith, salvation, immortality, and a messiah. But Christianity spread much more quickly. Why?
- Christianity had a well-defined organizational structure.
- Christianity claimed a moral authority that the government of the Empire lost when it began to rely on brute force.
- Christianity gave material support to its adherents, while the Empire was sucking them dry through taxes, price controls, and so on.

The final struggle for the mind of man in the ancient world wasn’t between Jesus and Aristotle. It was between Jesus and Plotinus. Followers of both rejected reason, embraced mystical experience, condemned life on earth, and looked toward a better life in the hereafter. Christianity won because it had more emotional appeal and a better organization.
Next week: the final post in this series, on the art of the late Empire and the Fall of Rome.