One of the most immediately evocative terms out there is "Greco-Roman." Its meaning is pretty clear: it refers to things of a
Greek and Roman nature, specifically regarding ancient concepts. Due to its general nature, however, the term has the
unintended side effect of sometimes being unintentionally misleading or at the very least oversimplifying ideas that need more than a cursory
two-word descriptor. In some instances, such as "Greco-Roman wrestling" or "Greco-Roman sculpture," the term is completely sufficient to
convey an accurate meaning. It's less clear in others, specifically in the realm of what is referred to as Greco-Roman mythology or Greco-Roman
religion.
It's something of a myth in and of itself that Greeks and Romans shared the same gods under different names; typically this finds currency
through discussions about how the Greek Zeus became the Roman Jupiter or how the Greek Heracles became the Roman Hercules or any other
number of examples. In some instances (such as that of Heracles/Hercules), an existing Greek myth or god was adapted for a Roman audience,
essentially unchanged except for relevant names. In the case of the god Apollo, he was simply inserted into the Roman pantheon, name
unchanged. For the most part, however, the relationship between Greek and Roman gods is actually reversed; the pre-existing Roman Jupiter was
made to have the attributes of the Greek Zeus, leading in some instances to serious inconsistencies between the mannerisms and stories within the
two traditions.
Both the Greek and Roman religions have common roots in the proto-Indo-European religion, meaning that their gods
and stories are ultimately derived from the same source that also gave us Hinduism, the ancient Germanic religion, and
Celtic mythology, among many other traditions. It should make sense, then, that there would be similarities between them. Likewise, it's not as
if Greece and Italy are worlds apart, they're separated chiefly by a small bit of water, so exchanges between their peoples were known and
documented for centuries before the rise of Rome as an important political entity. The Greeks and Romans also did not exist in cultural vacuums;
they had regular contact with non-Indo-Europeans, and so absorbed many of their traditions as well.
Aside from the proto-Indo-European religious heritage, the main outside influences on the development of the ancient Greek religion came from
the eastern Mediterranean region, especially Egypt, Asia Minor, and the Levant. For the ancient pre-Romans (whom we'll call Latins for
now), the biggest single pre-Greek influence on their religion was a non-Indo-European people known as the Etruscans. The Etruscans were not
indigenous to the area, but by the ninth century BC, they were in control of some of the most important city-states in central Italy, a region
that to this day bears a version of their name, Tuscany. Nobody really knows where the Etruscans came from, but it is variously theorized that
they originally came from Turkey, or were refugees fleeing the collapse of the Minoan civilization, or that they were related to the people
who became the Basques of southern France and northern Spain. Regardless of where they came from, they were there and they spoke a non-
Indo-European language, but as a result of contacts with both the Greeks and the Latins, they had gods that were primarily Indo-European in name,
although not necessarily in their attributes.
It is actually pretty simple to cut through the fat and see which gods were native to the Latins and which ones were not based on their names:
Apollo, Pluto, Proserpina, and others with Greek or Greek-derived names were either later additions or changes to existing gods that filled
similar functions. Pluto, for example, is said to be the Latin equivalent of the Greek Hades, god of the underworld, but in reality, the word
"Pluto" is just a version of the euphemistic epithet the Greeks used to refer to him, plutus, meaning "wealthy." This tradition was
upheld in Latin with Pluto being called Dives, which has the same meaning. It was taboo to refer to Hades by name, so when he was inserted into
the Roman pantheon, it was with the name that was commonly used to refer to him. This is true of his wife, Proserpina, whose name is an even more
obvious transliteration of the Greek Persephone. The Romans in fact already had a native underworld deity called Dis Pater who shared similar
attributes with Hades, but who was usually recognized as a distinct entity. The name is of extreme antiquity, being clearly related to the
Sanskrit Dyauspitar and even the later Latin Jupiter, all of whom derive ultimately from a proto-Indo-European god called something like
Dyeus-Phter.
As mentioned earlier, the Greeks themselves were of course not immune to outside influences on their religion. Aphrodite, the goddess of
sex and beauty, has a name that is most likely not Indo-European in origin. Hesiod seemed to believe that her name was a compound meaning
"rising from the foam," which would accord with the story of her birth from the interaction of Uranus' castrated genitals with the sea, but it
is worth noting that while this motif is common in other Indo-European religions (Hinduism and Hittite mythology in particular), she was
confusingly given a second origin story later on that has her as the daughter of Zeus rather than his aunt (which is what she would be if she
were a daughter of Uranus and thus a sister to Cronus, Zeus' father). Hesiod's etymology is specious however and has only limited support. The
manner of worship of Aphrodite (specifically temple prostitution) suggests an Eastern origin similar to Ishtar or Astoreth. Her relationship with Adonis, a version of the Semitic deity Tammuz married to Astoreth, underscores the Oriental connection.* The Latin
Venus, by contrast, has a clear etymology that relates the goddess to words such as venal, venereal, venerable, etc; her name is distantly
related to the Sanskrit vana, meaning "attraction." Neither the Latins nor their more specifically Roman descendants approved of sexualized
religious worship, meaning that Venus was worshipped more conservatively either in the home or with more traditional sacrifices, even after the
Hellenizing period when the association between Venus and Aphrodite was made more concrete (and indeed, after conquering much of the
Hellenistic world, Roman consuls and emperors would periodically have to ban the practice of temple prostitution in the East).
One of the most striking disconnects between supposedly related gods was the one that existed between the Greek Ares and the Roman Mars.
Down to his name, Ares is Greek in nature, as the name ultimately derives from an archaic Greek word ara, meaning "destruction" - a fitting name
for the god of war. Mars is slightly more obscure, being descended from the Etruscan Maris, originally a male agricultural deity. Ares was not
just the god of war, but rather the god of brutal, frenzied war. Ares in fact functions more as part of a duo than as a single being, his other
half being his half-sister Athena. Whereas Ares was wild, passionate, and destructive, Athena was calm, virginal, and strategic. This
is why there are more statues and temples dedicated to Athena than to Ares, the latter of whom was regarded by the Greeks as something of a
negative force while Athena was praised for her wisdom and restraint. It's not exactly clear why or at what point Mars shifted to war from
fertility, but likely it had to do with another early Latin god, Quirinus, who was regarded as a protector of the people and later became
considered a particular attribute of Mars rather than a deity in and of himself. Regardless, the Roman Mars was viewed much more positively than
the Greek Ares, being as he was considered a protector rather than a destroyer, and he was even known archaically by the epithet Marspiter,
meaning "father Mars" (see also Dis Pater and Jupiter, a contraction of Iovus Pater). The goddess Minerva, the closest given equivalent to
Athena, was originally a moon goddess of the Etruscans called Menrwa. She was considered a goddess of wisdom and had Athena's other attributes
laid on top of her later on.
Another odd identification is the one that exists between the Greek Cronus and the Latin Saturn. In Greek religion, Cronus was the son of
Uranus and the father of Zeus, an intermediary deity known as a Titan. While Uranus was probably really worshipped at some point (he is a
version of the oldest Indo-European deity, the sky, and he is likely equivalent to the Sanskrit Varuna) and we know for sure that Zeus
eventually supplanted him, there has never been any evidence that Cronus was ever actually venerated and if so, his worship was of such
negligible prominence that no cult sites of his have survived. Cronus is a strange figure, being simultaneously the liberator of heaven from
his father's tyranny and a child-eating tyrant in his own right. He ruled over what Hesiod and others termed the Golden Age, a time in which
man lived freely with god in a peaceful world that had no need of laws, but was apparently so terrible that he and all the other Titans needed to
be overthrown by his sons and locked up in chains for eternity. The schizophrenic depiction of Cronus is strange enough, but when you add to it
the fact that his name has no discernible Greek or otherwise Indo-European etymology, it becomes clear that he was likely the product of a Near
Eastern (possibly Semitic) deity mixed with perhaps other indigenous god or figure whose name has been lost to us. What Cronus and Saturn had
chiefly in common is that they were regarded as gods of the harvest, and their main attribute was the scythe. The scythe was the weapon
Cronus used to castrate Uranus while the scythe was rather more innoccuously the tool Saturn used to harvest grain. The early Latins did not
consider Saturn to have been overthrown and imprisoned by Zeus, and he was in fact freely venerated by them and their Roman descendants,
especially during the Saturnalia, a festival of loose morals that recreated and celebrated the Golden Age. The Greeks had a similar festival,
the Kronia, but they did not look at Cronus as a figure deserving of worship.
There are several other examples of this type, such as the fact that the Greek Poseidon was a god of the sea while the Roman Neptune was a
god of the river, but there were other deeper differences as well. General attitudes about religion in general were highly divergent between the
Greeks and Romans. While much can be (and has been) said about the bad behavior of the Romans, they were an entirely more conservative bunch than
the Greeks. Initially, the Italian economy was based on agriculture while the Greek economy was based on maritime trade; this set up a
dichotomy between the Greeks and the Romans that pitted a cosmopolitan group of merchants against a landed gentry uncomfortable
with change. It was through the conquest of Greece and expanded commercial ties between the two peoples that eventually led the Romans to place a
Hellenic layer over their native gods. They were not, however, on the same page as it related to worship and other rites.
As stated above, the Romans disapproved of the sexual worship of Aphrodite, as it was felt to be beneath their dignity to subject their women
to temple prostitution. Temple prostitution is a form of religious worship designed to pay for the upkeep of particular shrines in which the
devotees of a particular deity travel to a temple and have sex with the first person who offers them payment for it, regardless of the customer
or the amount offered. This was a typically Eastern form of worship peculiar to female deities and almost always practiced by female believers.
Romans were very class conscious, so the thought that a slave could go to the temple of Venus and offer a brass obol to have sex with a Roman
noblewoman was offensive in the extreme. Also, prostitution in Rome was heavily taxed, and traditionally the state did not collect proceeds
from temple prostitution, so that made it even worse. The Romans also disapproved of the Bacchic rites, which were again chiefly female affairs.
Bacchus was the Romanized version of the Greek god Dionysus, but like Pluto/Hades, his name was simply a Greek epithet used to describe him.
In this instance, Dionysus Bakkhos was Dionysus the Crazed. Dionysus was himself a non-indigenous deity, with his name unhelpfully meaning "son
of god." He was considered the god of wine and ecstasy and he certainly lived up to that reputation. At the Bacchic festivals, women would
dance and drink themselves into states of crazed ecstasy. While initially only a yearly festival, the Bacchanalia eventually became a weekly
phenomenon. These festivals were eventually banned by the Romans as being indecent and disruptive, and they were only permitted on very special
occasions and then only by specific orders from the Emperor or Senate.
Another area in which the Greeks and Romans disagreed was that of prophecy. There was a long tradition in the Hellenistic world of
consulting oracles to learn the future. The most famous of these, of course, was Apollo's Oracle of Delphi. This was considered one of the
most sacred spots in the ancient world, even by people who were not necessarily Greek or Hellenistic. The Anatolian king Croesus was said to
have visited the Oracle of Delphi to determine whether or not he should to go war with the Persian Empire. The oracle responded rather
ambiguously that if he did, he would "destroy a great kingdom," without specifying which one (in the event, it was Croesus' kingdom that fell).
Soothsaying and fortune telling were common to the Greeks as well, having been imported from the Babylonians. While the Romans were
tolerant of the oracles because of their prestige, they were not fond of what they called "superstitions" and therefore banned astrology and
related magical arts. There were a few reasons for this. The Romans had inherited augury from the Etruscans, which was the closest thing to a
"scientific" form of prophecy in the ancient world. Augury involved sacrificing an animal and inspecting its entrails for signs relevant to the
question being asked. While it might seem silly now, augury was believed to be more wholesome because it was systematic and less ambiguous than
personal prophecy. Imperial politics also played a role in this: the second Roman Emperor, Tiberius, outlawed fortune telling on the pain of death and subsequent Emperors
upheld this prohibition. While most forms of fortune telling are innoccuous if not frivolous, the rulers of the Roman world were concerned that
people would use astrology to determine the date of an Emperor's death and/or his successor and then use that information to their nefarious
advantage. This attitude continued into the Christian era of the empire and witchcraft was a common charge that carried with it
the death penalty in post-Roman Europe up until the 17th century.
A strange area of divergence was that of emperor worship. To the early and classical Greeks, it was hubris for a mortal to accept or to have
pretensions of divine honors. During the Hellenistic era, however, non-Greek Eastern influences began to predominate in the matter of
apotheosis. While there was nothing odd about a person dying and subsequently becoming a god, being a living god was an entirely different
issue for the Greeks. In the areas of the Persian Empire that had been conquered by Alexander the Great and then ruled over by his successor
generals, king worship was both natural and expected. In Ptolemaic Egypt, the Ptolemies all claimed the Pharaonic tradition of divine
kingship. By the time of Rome's conquest of the Greek world, then, the notion was accepted in the East. On coinage from this period in the East,
Hellenistic rulers have themselves described as "basileous basileoun (king of kings)," "soter megas (great savior)," "epiphanies (guided by the
gods)," and finally "theos (divine)." In keeping with the more conservative nature of Roman religion, it was frowned upon in the West. The only
mortal that the ancient Romans accepted as divine before the Imperial period was their founder Romulus, and even then only as a version of
Quirinus, who was of course an avatar of Mars. What we might call the imperial cult was created during the reign of the first Emperor
Augustus, who had previously had his great uncle Gaius Julius Caesar deified by order of the Senate. During his lifetime, Augustus was
worshipped as a god in the East by his Hellenistic subjects. While he never specifically asked for or promoted this, neither did he do anything
to prevent its spread. In time, worship of the Roman emperor became compulsory, although in an indirect fashion. While the Eastern Empire readily
embraced the emperor as a living god, the West was slightly more skeptical, so a cult to the emperor's genius (his spirit, not intelligence)
was used there. All subjects were expected to make sacrifices to the state gods of the Roman empire, including the Imperial Spirit, for the
purpose of protecting the life of the emperor. For obvious reasons, Emperors ceased to be deified after the Christian era. The late first century Emperor Domitian used the title "dominus et deus," literally meaning "lord and god," and subsequent rulers occasionally adopted this. Christian Emperors modified the title somewhat, giving rise to the ubiquitous European royal style "by the Grace of God."
One of the most paradoxically important but least talked about differences between the Greeks and Romans in religion had to do with
philosophy. Following the examples of Oswald Spengler and Julius Evola, monotheism did not start with Christianity in the Greek world,
but rather immediately before and during the Hellenistic era. Perhaps more appropriately, the intellectual tendency toward monotheism started
around this time, led by thinkers such as Plato in the early 4th century BC. Plato and his followers didn't believe in the literal truth of the
gods as depicted in the works of Homer and Hesiod and it is entirely possible that they did not accept the existence of the gods except as
Platonic ideals. In the Republic, Plato described the highest ideal as being the Good, claiming that all other concepts emanated from
it. As time went on, the Greek intellectual elite embraced this idea, which eventually led to the development of what we call Neoplatonism in
the third century AD. Neoplatonism took Plato's notion of a prime mover and built a religion around it, sometimes including the traditional
gods as ideals and sometimes not. While originally intended as a counter to the growth of Christianity, Platonism would ironically be used as a
source of philosophical support for later Christian and even Muslim authors looking for historical predecessors to their faiths. During
the middle and late Republican period in Rome, the Senatorial patrician class looked disapprovingly on Greek philosophy for exactly this
reason; for people like Cato the Elder, Greek philosophy undermined traditional notions of religion and encouraged people not to be
sufficiently reverent since the gods were not, after all, literal beings with specific functions or influences upon daily life. Wealthy Romans
had their sons educated primarily by Greeks but were careful to make sure that philosophical instruction was in accordance with their values.
While it's easy to reduce the differences between Greece and Rome religiously to an East versus West mindset, the truth is a little bit more
complex. Since the Roman absorption of Greek mythology was basically complete by the third century BC, it's hard to parse out what similarities
existed prior to that time and which ones were inserted at a later date, meaning that a fuller exploration of this topic on a god by god basis is
basically impossible. Similarly, laws banning paganism in both the Western and Eastern Roman Empires starting in the late fourth century AD
naturally would have had the efffect of causing us to lose important primary documents detailing modes of worship. From what we do know, however,
it's difficult to claim a monolithic religious identity for these two separate yet inexorably intertwined peoples we call the Greco-Romans.
* Thanks to drownzsurf for bringing this up!