In the Roman world, religion was a national affair. Worship of the national gods was not only piety, but also patriotism. Patriotism and religion were inseparably connected. Support of the gods of Rome, even where personal faith in them had been undermined, was considered to be the duty of every loyal citizen.
The political aspect of Roman religion appears most clearly in the worship of the Roman emperors. This remarkable development appears from the beginning of the empire. Augustus, indeed, refused to receive divine honors, at least in the west. But in the east even he was worshiped, and as time went on the reluctance of the emperors disappeared. Some of the worst of the emperors were most insistent upon their own divinity.
Perhaps the first impulse of the modern man is to regard the Cæsar cult simply as a particularly despicable form of flattery. In reality it was more than that. It was not established by imperial edict. It was not dictated primarily by servile fear. The Greek inhabitants of the empire really regarded Augustus as their saviour. And so he was, as far as any man could be. He saved them from the miseries of civil war, and from the rapacity of the degenerate republic; he gave them peace and happiness. And they responded by regarding him as a god.
To them it was natural. To them it was nothing new. Alexander the Great had been regarded as a god long before the Christian era. His successors in Syria and in Egypt had also received divine honors. To the genuine Romans, the thing did not come so easy. The Cæsar cult, at least at first, was not developed in the west. But even the Romans could worship the emperor's "genius" or spirit, and from that to the actual worship of the emperor was but a step. Essential to the whole process of deification, both in Rome and in the east, was the close connection in ancient thinking between deity and humanity, and between religion and the state. If patriotism is religion, then the king is a god.
The Cæsar cult was the most palpable incorporation of the state religion. Worship of the emperor, therefore, might well be the test of loyalty to Rome. It could be practiced by skeptics and philosophers. It could be practiced by the devotees of all religions--save two. Jews and Christians alone could not bow at the emperor's shrine, for their God was a God who could brook no rival. He was not merely the greatest among many. He was the only Lord, Maker of heaven and earth.