Ancient Roman religion encompasses the collection of beliefs and rituals practised in ancient Rome in the form of cult practices. It is therefore the practical counterpart of Roman mythology. Within the Roman world, religious practice varied enough so that one might speak of Roman religions. The cult practices of Rome extended across Italy with the rise of the Roman Empire. These religions were polytheistic, and as such are sometimes referred to as "pagan".
The Romans originally followed a rural animistic tradition, in which many spirits were each responsible for specific, limited aspects of the cosmos and human activities, such as ploughing. The early Romans referred to these as numina. Another aspect of this animistic belief was ancestor, or genius, worship, with each family honoring their own dead by their own rites. Rome had a strong belief in gods. When they took over Greece, they inherited the Greek gods but fused them with their Roman counterparts.
Based heavily in Greek and Etruscan mythology, Roman religion came to encompass and absorb hundreds of other religions, developing a rich and complex mythology. In addition, an Imperial cult supplemented the pantheon with Julius Caesar and some of the emperors.
Under the Empire, religion in Rome evolved in many ways. Numerous foreign cults grew popular, such as the worship of the Egyptian Isis and the Persian Mithras. The importance of the imperial cult grew steadily, reaching its peak during the Crisis of the Third Century. Also, Christianity began to spread in the Empire, gaining momentum in the second century. Despite persecutions, it steadily gained converts. It became an officially supported religion in the Roman state under Constantine I. All cults except Christianity were prohibited in 391 by an edict of Emperor Theodosius I. However, even in the fourth and fifth century Roman paganism kept its vitality. Temples were still frequently visited, ancient beliefs and practices continued. As the original Roman religion faded, many aspects of its hierarchy remain ingrained in Christian ritual and in Western traditions.
But Fetishism must very early have developed into Animism, the feeling of the sacredness of the object into the sense of an indwelling spirit. In the animistic attitude we have indeed the true background of the genuine Roman religion; but its characteristic and peculiar development is a kind of "higher Animism," which can associate the "spirit" not merely with visible and tangible objects, but with states and actions in the life of the individual and the community. No doubt the later indigitamenta ("bidding-prayers") which give us detailed lists of the spirits which preside over the various actions of the infant, or the stages in the marriage ceremony, or the agricultural operations of the farmer, are due in a large measure to deliberate pontifical elaboration, but they are a true indication of the Roman attitude of mind, which reveals itself continually in the analysis of the cults of the household or the festivals of the agricultural year.
To these numina of the sacred places must be added two other important conceptions, that of the Lar familiaris and the Genius. The Lar familiaris has been regarded as the embodiment of all the family dead and his cult as a consummation of ancestor-worship, but a more probable explanation regards him as one of the Lares who had special charge of the house or possibly of the household servants (familia); for it is significant that his worship was committed to the charge of the vilica. The Genius is originally the "spirit of developed manhood," the numen which is attached to every man and represents the sum total of his powers and faculties as the Juno does of the woman: each individual worships his own Genius on his birthday, but the household-cult is concerned with the Genius of the pater familias. The established worship of the household then represents the various members of the family and the central points of the domestic activity; but we find also in the ordinary religious life of the family a more direct connexion with morality and a greater religious sense than in any other part of the Roman cult. The family meal is sanctified by the offering of a portion of the food to the household numina: the chief events in the individual life, birth, infancy, puberty, marriage, are all marked by religious ceremonial, in some cases of a distinctively primitive character. The dead, too, though it is doubtful whether in early times they were actually worshipped, at any rate have a religious commemoration as in some sense still members of the family.
Organization showed itself in the fixing of the annual calendar and the development of the character and functions of the priesthood, and as we should expect, in a new conception of the legal relation of the gods to the state. In the earlier stage - whose notions of course still persist alongside of the state religion - each household has its own relations to its numina: now the state approaches the gods through its duly appointed representatives, the magistrates and priests. Their presence is typical of that of the whole people, and the private citizen is required to do no more on festival days than a ceremonial abstinence from work. It is obvious that the state religion has a less direct connexion with morality and the religious sense than the worship of the household, but it has its ethical value in a sense of discipline and a consecration of the spirit of patriotism.
Tradition always assigned to the last three kings of Rome a connexion with the mysterious people of Etruria, and their influence at this period though not very definite was certainly extensive. To them, possibly through the mediation of Falerii, a Latin town on the Etruscan border, was due the introduction of Minerva, who, as the goddess of handicraft and protectress of the artisan gilds, was established in a temple on the Aventine. Soon, however, she found her way on to the Capitol, and there a new Etruscan triad, Jupiter, Juno and Minerva, possibly going back from Etruria to Greece, was enshrined in a magnificent new temple built by Etruscan workmen and decorated in the Etruscan manner. In this temple the deities were represented by images, and on its dedication day, September 13th, at the novel festival of the epulum Jovis, the images were adorned and set out as partakers of the feast, a proceeding wholly foreign to the native Roman religion.
Secondly, in war and peace Rome formed relations with her neighbours of Latium, and, as a sign of the Latin league which resulted, the cult of Diana was brought from Aricia and established on the Aventine in the "commune Latinorum Dianae templum": about the same time was built the temple of Jupiter Latiaris on the Alban mount, its resemblance in style to the new Capitoline temple pointing to Rome's hegemony. So great was Rome's sense of kinship to the Latins that in two cases Latin cults were introduced inside the pomoerium: the worship of Hercules, which came from Tibur in connexion with commerce, was established at the ara maxima in the Forum Boarium, and the Tusculan cult of Castor as the patron of cavalry found a home close to the Forum Romanum: both these deities were originally Greek. Other Italian cults introduced at this period were those of Juno Sospes and Juno Regina, Venus and Fortuna Primigenia, a goddess of childbirth who came from Praeneste.
Later on in the same period contact with the cities of Magna Graecia brought about the wide-reaching introduction of the Sibylline books. Whatever may be their origin - and they came from Cumae - they were placed in the Capitoline temple under the care of a special commission of two (duoviri sacris faciundis, later decemviri and quindecimviri), and their "oracles," which were referred to in times of great national stress, recommended the introduction of foreign cults. In 493 BC, at a time of serious famine, they ordered the building of a temple to the Greek triad Demeter, Dionysus and Persephone, who were identified with the old Roman divinities Ceres, Liber and Libera: Apollo must have come with or before the books themselves, though his temple was not built till 433 BC: Mercury followed, Asclepius was brought from Epidaurus to the Tiber Island in 293 BC, and Dis and Proserpina, with their strange chthonic associations and night ritual, probably from Tarentum in 249 BC. With new deities came new modes of worship: the graecus ritus, in which, contrary to Roman usage, the worshipper's head was unveiled, and the lectisternium, an elaborate form of the "banquet of the gods." In this period, then, we find first a legitimate extension of cults corresponding to the needs of the growing community, and secondly a religious restlessness and a consequent tendency to more dramatic forms of worship.
Meanwhile a corresponding change was taking place in the attitude of the educated classes owing to the spread of Greek literature. The knowledge of Greek mythology, to which they were thus introduced, set poets and antiquarians at work in a field wholly foreign to the Roman religious spirit, the task of creating a Roman anthropomorphic mythology. This they accomplished partly by the popular process of adoption and identification, partly by imitative creation. In this way grew up the "religion of the poets," whose falseness and shallowness was patent even to contemporary thinkers. But more important was the influence of philosophy, which led soon enough to a general scepticism among the upper classes. Its first note is struck by Ennius in his translation of the Sicilian rationalist Euhemerus, who explained the genesis, of the gods as apotheosized mortals. In the last century of the Republic the two later Greek schools of Epicureanism and Stoicism laid hold on Roman society. The influence of Epicureanism was destructive to religion, but not perhaps very widespread: Stoicism became the creed of the educated classes and produced several attempts, notably those of Scaevola and Varro, at a reconciliation of philosophy and popular religion, in which it was maintained that the latter was in itself untrue, but a presentation of a higher truth suited to the capacity of the popular mind.
The result on the old religion was twofold. On the one hand, worship passed into formalism and formalism into disuse. Some of the old cults passed away altogether, others survived in name and form, but were so wholly devoid of inner meaning that even the learning of a Varro could not tell their intention or the character of the deity with whom they were concerned. The old priesthood, and in particular the flaminia, came to be regarded as tiresome restrictions on political life and were neglected. On the other hand, as the result in part of the theory of Stoicism, religion passed into the hands of the politicians: cults were encouraged or suppressed from political motives, the membership of the colleges of pontifices and augurs, now conferred by popular vote, was sought for its social and political advantages, and augury was debased till it became the meanest tool of the politician. In the general wreck of the old religion, little survived but the household cult, protected by its own genuineness and vitality.
The divinity of the emperor and the cult surrounding him were a very important part of religion in the Roman Empire. In an effort to enhance political loyalty among the populace, subjects were called to participate in the cult and revere the emperors as gods. The emperors Augustus, Claudius, Vespasian, and Titus were deified; after the reign of Marcus Cocceius Nerva, few emperors failed to receive this distinction.
The Roman religion in the empire tended more and more to center upon the imperial house. Especially in the eastern half of the empire, imperial cults became very popular, and the cult complex became one of the focal points of life in the Roman cities. As such it was one of the major agents of romanization. The central elements of the cult complex were located next to a temple; a theatre or amphitheatre for gladiatorial displays and other games and a public bath complex. Sometimes the imperial cult was added to the cults of an existing temple or celebrated in a special hall in the bath complex.
Evidence for the importance of the imperial cult include the "Achievements of the Divine Augustus" (Res Gestae Divi Augusti), written upon two large bronze pillars once located in Rome, Roman coins where the Emperor is portrayed with a halo or nimbus, and temple inscriptions such as "Divine Augustus Caesar, son of a god, imperator of land and sea..." (Roman Temple Inscription in Myra, Lycia).
As the Roman Empire expanded, and included people from a variety of cultures, more and more gods were incorporated into the Roman religion. The legions brought home cults originating from Egypt, Britain, Iberia, Germany, India and Persia. The cults of Cybele, Isis, Mithras, and Sol Invictus were particularly important. Some of those were initiatory religions of intense personal significance, similar to Christianity in those respects.
St. Peter and St. Paul introduced Christianity to the Romans, after Jesus was believed to have died sometime between c. 30-33 AD. Christian missionaries traveled across the empire, steadily winning converts and establishing Christian communities. After the Great Fire of Rome in July 64, Emperor Nero (56-68) accused the Christians as convenient scapegoats who were later persecuted and martyred. From that point on, Roman official policy towards Christianity tended towards persecution. The Roman authorities suspected Christians of disloyalty to the Emperor and of committing various crimes against humanity and nature. Persecution recurred especially at times of civic tensions and reach their worst under Diocletian (284 to 305). Constantine I (324-337) ended the persecutions by establishing religious freedom through the Edict of Milan in 313. He later convened the historic First Council of Nicaea in 325, a year after ending the civil war of 324 and emerging as the victor in the war of succession. This First Council of Nicaea was formed to oppose Arius who had challenged the deity of Jesus Christ. The result was the branding of Arianism as a heresy. Christianity, as opposed to other religious groups, became the official state religion of the Roman empire on February 27, 380 through an edict issued by Emperor Theodosius I in Thessalonica and published in Constantinople. All cults, save Christianity, were prohibited in 391 by another edict of Theodosius I. Destruction of temples began immediately. When the Western Roman Empire ended with the abdication of Emperor Romulus Augustus in 476, Christianity survived it, with the Bishop of Rome as the dominant religious figure, but see also Pentarchy.
Lay Christians took advantage of new anti-Graeco-Roman polytheism laws by destroying and plundering the temples. Temples that survived were converted into Christian churches: the Pantheon is the most notable example, having once been a temple to all the gods and later becoming a church in honor of all the saints. Many of the buildings in the Roman Forum were similarly converted, preserving the structures if not their original intent.
Later on, the emperor Julian the Apostate attempted to reverse the process of Christianization and bring back the native forms of polytheism, but his death in Persia caused the empire to once again fall under the power of Christian control, this time permanently.
The distinctions among philosophy, religion, cult and superstition that would be made by an educated Roman of the 1st century BC can be read in Lucretius, a philosopher following Epicurus. Most educated Romans were Stoic in the outlook on life. The transference of the anthropomorphic qualities of Greek gods to Roman ones, and perhaps even more, the prevalence of Greek philosophy among well-educated Romans, brought about an increasing neglect of the old rites, and in the 1st century BC the religious importance of the old priestly offices declined rapidly, though their civic importance remained. Many men whose patrician birth called them to these duties had no belief in the rites, except perhaps as a political necessity. Nevertheless, the positions of pontifex maximus and augur remained coveted political posts. Julius Caesar used his election to the position of pontifex maximus to influence the membership of the priestly groups.
Before the rise of Christianity, in most cults orthopraxy (doing the right things), was more important than orthodoxy (believing the right things). This is the case in Roman religion too. Daily life was inextricably linked to religious practice.
The Roman religious calendar reflected Rome's hospitality to the cults and deities of conquered territories. Roman religious festivals known from ancient times were few in number. Some of the oldest, however, survived to the very end of the pagan empire, preserving the memory of the fertility and propitiatory rites of a primitive agricultural people. New festivals were introduced, however, to mark the naturalization of new gods. So many festivals were adopted eventually that the work days on the calendar were outnumbered. Among the more important of the Roman religious festivals were the Saturnalia, the Lupercalia, the Equiria, and the Secular games.
Under the empire, the Saturnalia were celebrated for seven days, from December 17 to December 23, during the period in which the winter solstice occurred. All business was suspended, slaves were given temporary freedom, gifts were exchanged, and merriment prevailed. The Lupercalia was an ancient festival originally honoring Lupercus, a pastoral god of the Italians. The festival was celebrated on February 15 at the cave of the Lupercal on the Palatine Hill, where the legendary founders of Rome, the twins Romulus and Remus, were supposed to have been nursed by a wolf. Among the Roman legends connected with them is that of Faustulus, a shepherd who was supposed to have discovered the twins in the wolf's den and to have taken them to his home, in which they were brought up by his wife, Acca Larentia. See founding of Rome.
The Equiria, a festival in honor of Mars, was celebrated on February 27 and March 14, traditionally the time of year when new military campaigns were prepared. Horse races in the Campus Martius notably marked the celebration.
The Secular games, which included both athletic spectacles and sacrifices, were held at irregular intervals, traditionally once only in about every century, to mark the beginning of a new saeculum, or "era". They were supposed to be held when the last person who had witnessed the previous Secular games died, marking the beginning of a new era. The tradition, often neglected, was revived as a spectacle by Augustus and honoured by the poet Horace with a series of odes.