Roman Gods - Early Pantheism
Roman gods originated in the ancient "village" of Rome as the faceless and formless deities that supported farmers in their efforts with the land. The large number of Roman gods can most likely be explained by the pantheistic belief of "numen," which holds that gods and spirits inhabit places, objects and living things. The early Romans believed that everything in nature was inhabited by numina.
Even though the early Romans placed little importance on the personalities of their gods, they did care about their functions. The early Romans integrated their worship of gods into all aspects of their personal and public lives. Nothing better exhibits the extent of this worship in every day life as in the household cult of the Dii Familiaris. In this system, every family had a guardian spirit known as the Lar Familiaris. This spirit was honored at all family functions, including sacrifices at funerals. The creative force that engenders an individual and allows him or her to grow, learn and act morally was known as the Genius for men and the Luna for women. This spirit stayed with an individual until death. The worship of Roman gods in Dii Familiaris went as far as to assign a protector spirit to different areas of the house. For instance, Forculus protects the door, Limentinus the threshold, Cardea the hinges, and Vesta the hearth.
Roman Gods - Later Expansion
Roman gods began taking on the forms that we would recognize today during the dynasty of the Etruscan kings that ruled the city of Rome in the 6th century BC. During this period, the Romans adapted a group of three Etruscan gods as the focus of state worship. These gods were worshiped at the grand temple on the Capitoline Hill, and, as such, became known as the Capitoline triad. The triad consisted of Jupiter (Zeus), Juno (Hera), and Minerva (Athena). Once the rule of the Etruscan dynasty ended in 509 BC, Rome became a republic. The Roman Republic was ruled by two chief magistrates, each of whom was elected to a one-year term. During this period, the Capitoline temple became the focus of public worship.
As Rome's power grew and its sphere of influence expanded, the Roman Empire encountered the older and richer religious beliefs of the Greeks. The Romans also came into contact with the beliefs of other eastern Mediterranean Sea cultures. As a result, Romans began to adopt various foreign gods and religious customs. In many cases, gods and heroes from foreign cultures were given temples in Rome. The acceptance of Greek gods had the biggest influence on Roman religion. The earliest Greek gods adopted by the Romans were Castor and Polydeuces in 484 BC. Later in the 5th century BC, the Greek god Apollo was introduced. Apollo would eventually symbolize Roman virtue and austerity. Other Roman gods that took on Greek characteristics included Diana (Artemis), Mercury (Hermes), Neptune (Poseidon), Venus (Aphrodite), and Vulcan (Hephaestus).
As Rome continued to expand its political and geographic influence, Rome continued to assimilate a wider variety of religious beliefs and customs. In some cases, the assimilation of a foreign god was done to fit a particular role in Rome's expansion. This was the case for the goddess Cybele, whose worship was the direct result of the threat that Hannibal posed towards Rome. Even though Hannibal was eventually defeated, the worship of Cybele continued. The Romans also began to assimilate the belief in savior-gods from so called "mystery" religions. One of these was the Persian religion of Mithrasism. The Persian god Mithra (god of light and wisdom) offered salvation through the belief in an immortal soul. These religions became popular since they offered a greater sense of community than strict pantheism.
Roman Gods - Divine Emperors
The nature of Roman gods expanded again as the Roman Empire came into contact with the belief of divine kingship. At first, the Romans rejected the idea that a human ruler should be worshiped as a god. In 44 BC, Julius Caesar permitted a statue of himself with the inscription, "The unvanquished god," and declared himself dictator for life. That same year, Julius Caesar was killed by citizens who wanted to see Rome return to its earlier republican ideas. Caesar's heir, Octavian (Augustus), made himself the first emperor of Rome. However, he avoided any claim to being divine. In fact, the notion that the emperor was divine was ridiculed throughout much of the 1st century AD.
However, as the government of the Roman Empire became more autocratic and gave rulers almost unlimited power, emperors eventually accepted divine honors. This belief in the emperor's divine authority eventually led to the requirement of a sacrifice to the emperor as a sign of loyalty. The requirement of a sacrifice to the emperor became a significant source of conflict with early Christians. Christians refused to worship the emperor as god, and therefore, would not sacrifice to him. This led to persecution of the Christians by the Roman political authorities that enforced the practice. The period of worshiping Roman emperors as gods continued until the 4th century AD, when Emperor Constantine the Great became the first Roman emperor to convert to Christianity. In 392 AD, Emperor Theodosius I banned the practice of pagan religions in Rome altogether.