Roman imperial cult
The Roman imperial cult identified emperors and some members of their families with the divinely sanctioned authority of the Roman State. Its framework was based on Roman and Greek precedents, and was formulated during the early Principate of Augustus. It was rapidly established throughout the Empire and its provinces, with marked local variations in its reception and expression.
Augustus's reforms transformed Rome's Republican system of government to a de facto monarchy, couched in traditional Roman practices and Republican values. The princeps was expected to balance the interests of the Roman military, Senate and people, and to maintain peace, security and prosperity throughout an ethnically diverse empire. The official offer of cultus to a living emperor acknowledged his office and rule as divinely approved and constitutional: his Principate should therefore demonstrate pious respect for traditional Republican deities and mores.
A deceased emperor held worthy of the honor could be voted a state divinity by the Senate and elevated as such in an act of apotheosis. The granting of apotheosis served religious, political and moral judgment on Imperial rulers and allowed living emperors to associate themselves with a well-regarded lineage of Imperial divi from which unpopular or unworthy predecessors were excluded. This proved a useful instrument to Vespasian in his establishment of the Flavian Imperial Dynasty following the death of Nero and civil war, and to Septimius in his consolidation of the Severan dynasty after the assassination of Commodus.
The imperial cult was inseparable from that of Rome's official deities, whose cult was essential to Rome's survival and whose neglect was therefore treasonous. Traditional cult was a focus of Imperial revivalist legislation under Decius and Diocletian. It therefore became a focus of theological and political debate during the ascendancy of Christianity under Constantine I. The emperor Julian failed to reverse the declining support for Rome's official religious practices: Theodosius I adopted Christianity as Rome's state religion. Rome's traditional gods and imperial cult were officially abandoned.
Background
Roman
For five centuries, the Roman Republic did not give worship to any historic figure, or any living man, although surrounded by divine and semi-divine monarchies. Rome's legendary kings had been its masters; with their removal, Republican Romans could identify Romulus, the founder of the city, with the god Quirinus and still retain Republican liberty. Similarly, Rome's ancestor-hero Aeneas was worshipped as Jupiter Indiges. The Romans worshipped several gods and demi-gods who had been human, and knew the theory that all the gods had originated as human beings, yet Republican traditions were staunchly conservative and anti-monarchic. The aristocrats who held almost all Roman magistracies, and thereby occupied almost all of the Senate, acknowledged no human as their inherent superior. No citizen, living or dead, was officially regarded as divine, but the honors awarded by the state—crowns, garlands, statues, thrones, processions—were also suitable to the gods, and tinged with divinity; indeed, when the emperors were later given state worship, it was done by a decree of the Senate, phrased like any other honor.Among the highest of honors was the triumph. When a general was acclaimed imperator by his troops, the Senate would then choose whether to award him a triumph, a parade to the Capitol in which the triumphator displayed his captives and spoils of war in the company of his troops; by law, all were unarmed. The triumphator rode in a chariot, bearing divine emblems, in a manner supposed to be inherited from the ancient kings of Rome, and ended by dedicating his victory to Jupiter Capitolinus. Some scholars have viewed the triumphator as impersonating or even becoming a king or a god for the day but the circumstances of triumphal award and subsequent rites also functioned to limit his status. Whatever his personal ambitions, his victory and his triumph alike served the Roman Senate, people, and gods and were recognised only through their consent.
In private life, however, tradition required that some human beings be treated as more or less divine; cult was due from familial inferiors to their superiors. Every head of household embodied the genius – the generative principle and guardian spirit – of his ancestors, which others might worship and by which his family and slaves took oaths; his wife had a juno. A client could call his patron "Jupiter on earth". The dead, collectively and individually, were gods of the underworld or afterlife. A letter has survived from Cornelia, the mother of the Gracchi, expecting that when she was dead, her sons would venerate her as deus parens, a parental divinity; such piety was expected from any dutiful son.
A prominent clan might claim divine influence and quasi-divine honors for its leader. Death masks were made for all notable Romans and were displayed in the atria of their houses; they were used to represent their ghostly presence at family funerals. The mask of Scipio Africanus, Cornelia's father and victor over Hannibal, was stored in the temple of Jupiter; his epitaph said that he had ascended to Heaven. A tradition arose in the centuries after his death that Africanus had been inspired by prophetic dreams, and was himself the son of Jupiter.
There are several cases of unofficial cult directed at men viewed as saviors, military or political. In Further Spain in the 70s BC, loyalist Romans greeted the proconsul Metellus Pius as a savior, burning incense "as if to a god" for his efforts to quash the Lusitanian rebellion led by the Roman Sertorius, a member of the faction which called itself "men of the People". This celebration, in Spain, featured a lavish banquet with local and imported delicacies, and a mechanical statue of Victory to crown Metellus, who wore a triumphator's toga picta for the occasion. These festivities were organized by the quaestor Gaius Urbinus, but were not acts of the state. Metellus liked all this, but his older and pious contemporaries thought it arrogant and intolerable. After the land reformers Tiberius and Gaius Gracchus were both murdered by their opponents, their supporters "fell down" and offered daily sacrifice at the statues of the Gracchi "as though they were visiting the shrines of the gods". After Gaius Marius defeated the Teutones, private citizens would offer food and drink to him alongside their household gods; he was called the third founder of Rome after Romulus and Camillus. In 86 BC, offerings of incense and wine were made at crossroad shrines to statues of the still-living Marius Gratidianus, the nephew of the elder Marius, who was wildly popular in his own right, in large part for monetary reforms that eased an economic crisis in Rome during his praetorship.
Greek
When the Romans began to dominate large parts of the Greek world, Rome's senior representatives there were given the same divine honours as were Hellenistic rulers. This was a well-established method for Greek city-states to declare their allegiance to an outside power; such a cult committed the city to obey and respect the king as they obeyed and respected Apollo or any of the other gods.The cities of Ionia worshipped the Spartan general Lysander, when he personally dominated Greece, immediately following the Peloponnesian War; according to Plutarch, this was the first instance of ruler cult in Greek history. There were similar instances of divine cult to humans in the same century, although some rulers, like Agesilaus, declined it. Clearchus, tyrant of Heraclea, dressed up like Zeus and claimed godhood; this did not stop the Heracleots from assassinating him. Isocrates said of Philip II of Macedon that after he conquered the Persian Empire, there would be nothing for him to attain but to become a god; the city of Amphipolis, and a private society at Athens, worshipped him even without this conquest; he himself set out his statue, dressed as a god, as the thirteenth of the Twelve Olympians.
But it was Philip's son Alexander the Great who made the divinity of kings standard practice among the Greeks. The Egyptians accepted him as Pharaoh, and therefore divine, after he drove the Persians out of Egypt; other nations received him as their traditional divine or quasi-divine ruler as he acquired them. In 324 BC, he sent word to the Greek cities that they should also make him a god; they did so, with marked indifference, which did not stop them from rebelling when they heard of his death next year.
His immediate successors, the Diadochi, offered sacrifices to Alexander, and made themselves gods even before they claimed to be kings; they put their own portraits on the coinage, whereas the Greeks had always reserved this for a god or for an emblem of the city. When the Athenians allied with Demetrius Poliorcetes, eighteen years after the deification of Alexander, they lodged him in the Parthenon with Athena, and sang a hymn extolling him as a present god who heard them, as the other gods did not.
Euhemerus, a contemporary of Alexander, wrote a fictitious history of the world, which showed Zeus and the other established gods of Greece as mortal men, who had made themselves into gods in the same way; Ennius appears to have translated this into Latin some two centuries later, in Scipio Africanus' time.
The Ptolemies of Egypt and the Seleucids claimed godhood as long as they lasted; they may have been influenced in this by the Persian and Egyptian traditions of divine kings – although the Ptolemies had separate cults in Egyptian polytheism, as Pharaoh, and in the Greek. Not all Greek dynasties made the same claims; the descendants of Demetrius, who were kings of Macedon and dominated the mainland of Greece, did not claim godhead or worship Alexander.