Roman religion
Ancient Roman religion was a combination of several different practices and sets of beliefs.
The Romans originally followed an animistic rural tradition, in which many spirits (gods) were each responsible for specific, limited aspects of the universe. For example, there were different gods for ploughing, for horses, and for cattle.
Another aspect of this animistic belief was ancestor worship, with each family honouring their own dead by their own rites.
Early in the history of the Roman Republic, foreign gods were imported, especially from Greece, which had a great cultural influence on the Romans after they conquered it. In addition, the Romans connected some of their indigenous deities with Greek gods and goddesses.
Some important ones, with the Greek equivalents in brackets, were Jupiter (= Zeus), Juno (= Hera), Minerva (= Athene), Mars (= Ares), Vesta (= Hestia), Saturn (= Kronos), Vulcan (= Hephaistos), Cupid (= Eros), and Neptune (= Poseidon).
As the Roman Empire expanded, and included people from a variety of cultures, there were more and more gods. The legions brought home cults originating from Egypt, Britain, Iberia, Germany, and Persia. The cults of Cybele and Mithras were particularly important.
Along with this, the ancient Roman beliefs and practices continued, especially in and around Rome itself. This included the worship of the lares and penates (spirits specific to a family, with altars in the home), festivals such as the Lupercalia and Saturnalia, and a complex system of lucky and unlucky days.
Another important aspect of religion in Roman times was the divinity of the Emperor. More than just being the Pontifex Maximus (the head of the Roman Religion), Roman Emperors endorsed the various popular cult religions. In an effort to enhance political loyalty among the populace, they often called subjects to participate in the cults and revere the emperors as gods. Examples of this include "The Achievements of the Divine Augustus", which are two large bronze pillars in Rome inscribed with the deeds of Augustus, roman coins where the Emperor is portrayed with a halo or divine glow, temple inscriptions such as "Divine Augustus Caesar, son of a god, imperator of land and sea..." (Roman Temple Inscription in Myra, Lycia.
Chrisitianity eventually became the official state religion with Constantine I of the Roman Empire. Although, some consider this time period to be after the fall of the Roman Empire.