Christian Executions..

[Nathan Ross]

Part of the Emperor's right to rule was descent from, connection to the gods and often Emperor's were declared to be gods after death. To deny this was to deny the Emperor's right to rule.

Strictly speaking, dead emperors were made 'divine', which isn't quite the same as being turned into gods, more a matter of association - and not too many emperors claimed direct descent from the gods either. But there was something about the legitimacy of government in the Roman state's actions against Christianity, I think.

The first major persecution, under Decius in 249-250, was actually just an order for everyone in the empire to sacrifice to the emperor, and get a certificate for doing so. This seems to have been an attempt by Decius to halt the cycle of civil war and overall bad luck that plagued the third century, by a mixture of enforced observance of his rule and an appeal to divine intervention. It wasn't specifically directed against Christians, but they were the ones who fared worst, and most of the accounts of it come from Christian sources. Valerian picked up the idea, but the impulse seems to have been the same - an appeal to traditional Roman values and imperial stability through the public performance of sacrifice.

Diocletian and his colleages actually did associate themselves directly with the gods - the idea being that the harmony of imperial government was a reflection of the divine order. Since the gods they chose were the very traditional ones - Jupiter, Hercules, Mars, Apollo - this was clearly a traditionalist move; Diocletian in particular was a very pious man, and genuinely seemed to have believed that the fate of Rome was imperilled by the activities of godless Christians. This explains the comparative severity of his persecution edicts in 303-304, and the fact that they were directed solely at Christian worship.