Religion in Ancient Rome

Religion in ancient Rome encompasses the practices and beliefs the ancient Romans regarded as their own, as well as the many cults imported to Rome or practiced by peoples under Roman rule.

The Romans thought of themselves as highly religious, and attributed their success as a world power to their collective piety (pietas) in maintaining good relations with the gods. According to legendary history, most of Rome's religious institutions could be traced to its founders, particularly Numa Pompilius, the Sabine second king of Rome, who negotiated directly with the gods. This archaic religion was the foundation of the mos maiorum, "the way of the ancestors" or simply "tradition", viewed as central to Roman identity.

The priesthoods of public religion were held by members of the elite classes. There was no principle analogous to "separation of church and state" in ancient Rome. During the Roman Republic (509 BC–27 BC), the same men who were elected public officials served as augurs and pontiffs. Priests married, raised families, and led politically active lives. Julius Caesar became Pontifex Maximus before he was elected consul. The augurs read the will of the gods and supervised the marking of boundaries as a reflection of universal order, thus sanctioning Roman expansionism as a matter of divine destiny. The Roman triumph was at its core a religious procession in which the victorious general displayed his piety and his willingness to serve the public good by dedicating a portion of his spoils to the gods, especially Jupiter, who embodied just rule. As a result of the Punic Wars (264–146 BC), when Rome struggled to establish itself as a dominant power, many new temples were built by magistrates in fulfillment of a vow to a deity for assuring their military success.

Roman religion was thus practical and contractual, based on the principle of do ut des, "I give that you might give." Religion depended on knowledge and the correct practice of prayer, ritual, and sacrifice, not on faith or dogma, although Latin literature preserves learned speculation on the nature of the divine and its relation to human affairs. Even the most skeptical among Rome's intellectual elite such as Cicero, who was an augur, saw religion as a source of social order.

For ordinary Romans, religion was a part of daily life. Each home had a household shrine at which prayers and libations to the family's domestic deities were offered. Neighborhood shrines and sacred places such as springs and groves dotted the city. Apuleius described the everyday quality of religion in observing how people who passed a cult place might make a vow or a fruit offering, or merely sit for a while. The Roman calendar was structured around religious observances. In the Imperial era, as many as 135 days of the year were devoted to religious festivals and games (ludi). Women, slaves, and children all participated in a range of religious activities. Some public rituals could be conducted only by women, and women formed what is perhaps Rome's most famous priesthood, the state-supported Vestal Virgins, who tended Rome's sacred hearth for centuries, until disbanded under Christian domination.

The Romans are known for the great number of deities they honored, a capacity that earned the mockery of early Christian polemicists. The presence of Greeks on the Italian peninsula from the beginning of the historical period influenced Roman culture, introducing some religious practices that became as fundamental as the cult of Apollo. The Romans looked for common ground between their major gods and those of the Greeks, adapting Greek myths and iconography for Latin literature and Roman art. Etruscan religion was also a major influence, particularly on the practice of augury, since Rome had once been ruled by Etruscan kings.

Imported mystery religions, which offered initiates salvation in the afterlife, were a matter of personal choice for an individual, practiced in addition to carrying on one's family rites and participating in public religion. The mysteries, however, involved exclusive oaths and secrecy, conditions that conservative Romans viewed with suspicion as characteristic of "magic", conspiracy (coniuratio), and subversive activity. Sporadic and sometimes brutal attempts were made to suppress religionists who seemed to threaten traditional morality and unity, as with the senate's efforts to restrict the Bacchanals in 186 BC.

As the Romans extended their dominance throughout the Mediterranean world, their policy in general was to absorb the deities and cults of other peoples rather than try to eradicate them, since they believed that preserving tradition promoted social stability. One way that Rome incorporated diverse peoples was by supporting their religious heritage, building temples to local deities that framed their theology within the hierarchy of Roman religion. Inscriptions throughout the Empire record the side-by-side worship of local and Roman deities, including dedications made by Romans to local gods. By the height of the Empire, numerous international deities were cultivated at Rome and had been carried to even the most remote provinces, among them Cybele, Isis, Epona, and gods of solar monism such as Mithras and Sol Invictus, found as far north as Roman Britain. Because Romans had never been obligated to cultivate one god or one cult only, religious tolerance was not an issue in the sense that it is for competing monotheistic systems. The monotheistic rigor of Judaism posed difficulties for Roman policy that led at times to compromise and the granting of special exemptions, but sometimes to intractable conflict.

In the wake of the Republic's collapse, state religion had adapted to support the new regime of the emperors. Augustus, the first Roman emperor, justified the novelty of one-man rule with a vast program of religious revivalism and reform. Public vows formerly made for the security of the republic now were directed at the wellbeing of the emperor. So-called "emperor worship" expanded on a grand scale the traditional Roman veneration of the ancestral dead and of the Genius, the divine tutelary of every individual. Imperial cult became one of the major ways Rome advertised its presence in the provinces and cultivated shared cultural identity and loyalty throughout the Empire. Rejection of the state religion was tantamount to treason. This was the context for Rome's conflict with Christianity, which Romans variously regarded as a form of atheism and novel superstitio.

From the 2nd century onward, the Church Fathers began to condemn the diverse religions practiced throughout the Empire collectively as "pagan." In the early 4th century, Constantine I became the first emperor to convert to Christianity, launching the era of Christian hegemony. The emperor Julian made a short-lived attempt to revive traditional and Hellenistic religion and to affirm the special status of Judaism, but in 391 under Theodosius I Nicene Christianity became the official state church of the Roman Empire, to the exclusion of all others. Pleas for religious tolerance from traditionalists such as the senator Symmachus (d. 402) were rejected, and Christian monotheism became a feature of Imperial domination. Heretics as well as non-Christians were subject to exclusion from public life or persecution, but Rome's original religious hierarchy and many aspects of its ritual influenced Christian forms, and many pre-Christian beliefs and practices survived in Christian festivals and local traditions.