It is important to point out that the term “monotheism” takes in more ideologies than that of there being only “One God”, although that is its primary meaning. However, if we adhere strictly to that meaning, then we have no choice but to admit that none of the Israelite religions extant in the first century—Samaritanism, Judaism, early Christianity—were “monotheistic”. With the exception of a certain passage in Second Isaiah (Isaiah 45:7, to be specific), no passage of the Tanakh (the Old Testament to Christians) states that there is only one deity. Quite to the contrary, several passages refer to the “national” gods of other peoples in a context that makes clear the simple fact that their existence was taken for granted. Even Paul of Tarsus openly stated that Yahweh was not the only one: “Yes, there are many gods and lords. Yet for us there is only one God.” (1 Corinthians 8:5b-6a)
According to the Greek poet Hesiod of the eighth to seventh centuries BCE, the Arche (‘Source’, ‘Origin’, ‘Beginning’) of everything in the Universe was Chaos, then came Gaia (‘Earth’), Tatarus (‘Underworld’), and Eros (‘Love’). In his cosmology, these were the primordial gods. Chaos gave birth to Nyx (‘Night’) and Erebus (‘Darkness’).
Orphism, which goes back to at least the sixth century BCE, that Chronos (‘Undifferentiated Time’) produced Aether and Chaos, and that it is the former from which all things come.
Anaximander of Miletus in Ionia, c. 610-546 BCE, sometimes called the founder of Western philosophy, proposed as the Arke the Apeiron, or the Infinite. In his system, everything comes from the Apeiron and to the Apeiron all things eventually return. He developed this idea partly in reaction to his teacher and predecessor of the philosophical school at Miletus, Thales, who proposed the the substance from which all things came was water. He is also the first known to state that the Earth was a sphere hanging unsupported in space, as well as the fact that space has depth. Pythagoras may have been one of his students.
Plato (428-347 BCE) – Socrates’ pupil Plato promulgated the first monotheistic philosophy in the Hellenic world. His supreme being, though he never called its such, was a Being existing in three hypostases: Tagathon (‘The Good’), which he also called the Monad; Nous (‘Intellect’), and either the World-Psyche (‘Soul’) or the Demiurgos (‘Craftsman’), depending upon which of his works the discussion takes place. He also used the term To Hen (‘The One) for the Tagathon and for all three hypostases collectively as a single Being.
Plato’s The Good was for him the ultimate reality, but that did not mean for him that other gods did not exist. For him they did, but they were almost entirely irrelevant to human life.
Plato also introduced the doctrine of the immortality of the soul.
For Plato and succeeding Hellenistic philosophers, the Demiurgos was a benevolent being with good intentions.
Plato’s Three Hypostates pervaded much of Hellenistic philosophy and helped begat the doctrine of the Christian Trinity by way of the Gnostic teacher Valentinus.
All three Hypostases were in Plato’s doctrine subject to the Forms, or Ideas, the eternal patterns upon which reality shapes everything that is.
Aristotle (382-322 BCE) – Though more concerned with empirical evidence than metaphysical speculation, this student of Plato who shifted to empiricism after his teacher’s death taught the Peripatetics that there was an Uncaused Cause or Prime Mover that he sometimes called Ho Theos, or The God, the attached article implying that was the only one.
Zeno of Citium (334-262 BCE) – He and his followers, the Stoics, were pantheists. To them everything in the Cosmos was composed of Matter and Pneuma (‘Spirit’ or ‘Breath’), with the Divine Pneuma being the Source of pneuma for the rest of the cosmos. Zeno introduced the concept of Logos, equated with the Primal Fire, as the corporeal Cosmic Reason, immanent throughout the Cosmos, also called the World Psyche. Zeno and the Stoics also believed in the doctrine of eternal return, the idea that the cosmos would be destroyed and recreated over and over and over again, following the same pattern.
Antiochus of Ascalon (125-68 BCE) became the founder of Middle Platonism when he turned the Academy from its then current skepticism back toward its roots in the doctrines of Scorates and Plato. Antiochus combined the Demiurgos and the World-Psyche of two separate works of Plato with nearly identical functions into the single Logos (‘Reason’).
Plutarch of Chaeronea in Boeotia (45-120 CE) taught that there were two cosmic principles: Ho Theos (‘The God’), or the Monad, and the Indefinite Dyad. The Monad for Plutarch operates through Logos, or Reason, which is identified with the Demiurgos, while the Indefinite Dyad operates through the World Psyche (‘Soul’).
Neopythagoreanism combined Middle Platonism and Orphism to create a savior-god religion with celibacy, renunciation, communal living, and esoteric rituals.
Nigilius Figudius (98-45 BCE), a friend of noted Roman orator Cicero, revived the Pythagorean philosophy in the first century BCE, but it was Apollonius of Tyana (3-100 CE) who really got it restarted. Besides being a teacher of ethical behavior and orator, Apollonius, a contemporary of Jesus the Nazorean, was revered as a wonder-worker and healer was often compared in ancient times to the latter.
Neopythagoreans taught that the rational, ordered male Monad and the irrational, chaotic female Dyad produced everything else that is, starting with the Decad. The third principle, or hypostatis, of Harmony provided the balance between Monad and Dyad.
Numenius of Apamea (latter 2nd century), borrowed the Three Hypostases from the Platonists and taught that these were Tagathon or Ho On (‘The Being’) or First Intellect; the Nous or the Demiurgos; and the Cosmos or the World-Psyche.
The Hermeticists of ancient Egypt who arose in the first century CE were monotheists, even monists, who referred to their version of the deity as The One, Theos, or The All, whose agents in the cosmos were Nous and Logos.
Neoplatonism was in large part a reaction to doctrines later called Gnostic, particularly the latter’s idea of the Demiurgos as a malevolent rebel against The One which in Platonism had been a benevolent servant of The One.
The Neoplatonists introduced the concept of The One as “Beyond Being”, and also explicitly equated The One with Ho Theos, ‘The God’. The founder of this school, Plotinus of Rome (204-270), named the Three Hypostases as the One, the Divine Nous, and the Psyche, which he identified with the Demiurgos. He taught that Logos is the underlying plan tying it all together.
Iamblichus of Chalcis (245-325) conceived that the Three Hypostases were the transcendant One, the Monad, or the Nous; the superexistent One, the Dyad, or the Psyche; and, lastly, the Demiurgos. To make matters more complex, the first is a triad of triads, the second also a triad of triads, and the third is a hebdomad, of which one part is the Demiurgos proper and another the monad of Time. He also taught of an Unmanifest Absolute that was beyond the One, which he called the Ineffable.
Proclus Lycaeus of Athens (412-483) was more traditional than Iamblichus, teaching that the Three Hypostases were To Hen, or Tagathon; the Nous; and the Psyche. However, between To Hen and Nous Proclus inserted the Henads, which for him corresponded roughly to Plato’s Forms or Ideas. He postulated a threefold production of Nous from To Hen: mone (abiding), prohodos (procession), and epistrophe (return)
The parent of Western monotheism was Mazdayasna, or Zoroastrianism, influencing Hellenic thought through trade and cultural contact, then Hellenistic thought following the conquests of Alexander the Great of Macedonia. The monotheism of the Israelites in Samerina/Samereia, Yehud/Iudeia, and Egypt which later exerted an additional direct influence on Western thought also owed its existence to Mazdayasna.
According to the best ancient sources, in particular the Greek Fathers Gregory of Nazianus (whose father had been an adherent) and Gregory of Nyssa, the autonym of these deviant religious devotees was Theosebeis (‘God-reverers’). I say “deviant” because they only revered One True God in a society that was mostly polytheistic.
The worship of Theos Hypsistos (‘God Most High’), or just Hypsistos, was not so much a sect as a trend moving toward becoming a sect that began in the first century and began to make itself felt in the second. Its peak was in the latter half of the second through the fourth century.
At first glance, Hypsistos (‘Most High’) is almost certainly an Israelite appellation for the deity and derived from that influence. After all, that epithet is used one hundred seventy-five times in the Septuagint, the Tanakh of the Hellenistai, the Greek-speaking Jews of the Diaspora. In some cases, this assumption was very likely accurate, but in others there was little or no direct Jewish influence to explain its use, other than arising from the natural evolution of religion.
Some of the features of the worship of the Theosbeis include a prohibition against images for worship and against animal sacrifice. Their revulsion against anthropomorphism extended to refusing to call Theos Hypsistos “Father”. Women often played a prominent part in worship and governance. At most sites, prayer was held at sunset and sunrise, and worship took place outside of any building. Fire and light were major motifs, and numerous lamps have been found at sites with Hypsistarian inscription. Supposedly, they kept the Sabbath, or at least a Sabbath.
Another major feature were common meals, a feature of nearly all Hellenistic associations, such that Theosebeis were referred to in some documents as synklitai (‘those who eat together’), with one of them designated a triklinarchos (‘head of the symposion’).
Not all such inscriptions signal the presence of the cult. During the same time, the epithet Hypsistos came to be applied to many Hellenistic deities: Zeus Hypsistos, Serapis Hypsistos, Attis Hypsistos, Helios Hypsistos, Isis Hypsista, and Thea Hypsista (in Anatolia, referring to Cybele), for example. In some cases, inscriptions referred to one of the deities above. The presence of features of the monotheistic Theos Hypsistos cult listed above, or the lack thereof, would determine which is which.
The two main forms in which the Hypsistos epithet have been found are Theos Hypsistos and Zeus Hypsistos, both dominating different contiguous regions for the most part.
Zeus Hypsistos dominates the Hypsistos inscriptions in Greece, Caria, most of Macedonia, Dacia, Moesia, part of the Aegean islands, and coastal Anatolia. In a few cases where Zeus Hypsistos has been found, other features indicate a monotheistic cult influenced by the Theosebeis, such as lack of shrines for other deities, lack of images, lamps, etc. By the fourth century, a monotheistic cult centered on Dionysos Hypsistos had arisen in Cyprus.
Theos Hypsistos and simple Hypsistos predominate in Palestine, Phoenicia, Egypt, Delos, Thessaly, Thrace, Crete, Cyprus, Cimmeria, Anatolia, Phrygia, Lydia, the Bosphoros, the north shores of the Black Sea, and some of the Aegean islands. In some of these places, the inscription is to Theos Hypsistos Epekoos (‘He Who Hears’). The form Theos Hypsistos Pantokrator (‘Almighty’, or ‘Ruler of all’) was dominate in Cappadocia, the use of Pantokrator elsewhere almost exclusively limited to Jews and Samaritans, thus showing their influence.
The deity in Athens called Agnostos Theos (‘Unknown God’), mentioned in Acts of the Apostles and found elsewhere, may be another reference to Theos Hypsistos.
When Hadrian rebuilt the temple on Mount Gerizim near Flavia Neapolis after the Bar Kokhba War (132-135), he dedicated it to "Zeus Hypsistos". That the Samaritans used it unhesitatingly as their own lends credence to the idea that by the second century the two separate deities, Zeus Hypsistos and Theos Hypsistos, had merged in many places if not all, and that many Israelites equated any deity with the epithet Hypsistos with Yahweh.
By the end of the fifth century, with all the massive persecution by the state which was officially Christian, it had vanished.
The Latin-speaking western half of the empire had a counterpart to Theos Hypsistos, though not as much is known about it. This monotheistic deity was called Deus Aeternus (‘Eternal God’), and inscriptions to this deity have been found in Dacia, which had many military camps, Pannonia, southern Italia, Sicilia, and southeastern Hispania.
Just as the East has inscriptions to Zeus Hypsistos, the West has inscriptions to Jupiter Aeternus.
Its worth noting that the earliest of the ancient church orders, or rather their earliest known precursor, the De doctrina Apostolorum from the early first century CE, includes the following passage: ‘The way of life is this: first, you shall love the Eternal God (‘Deus Aeternus’) who made you; second, your neighbor as yourself, and what you do not want to befall you, do not do to another’.
This Latin document is an early version of the first six chapters of the much better known Greek-language Didache of late first century Syria. In the Didache, the “way of life” is the same, minus the specific reference to the “Eternal God”. With the De doctrina Apostolorum being widely acknowledged as having its origin among Hellenistic Jews, this use of a divine designation peculiar to the Deus Aeternus cult shows some cultural exchange between the two.
The West had its counterparts to the cult of Agnostos Theos in Deus Ignotus (‘God Unknowable’) and Deus Incognitus (‘God Inconceivable’).
The term “Gnostic” as a title for several highly diverse philosophical religious cults which flourished in the Mediterranean and Iranian world in the second through fourth centuries and survived in the former until the fifth century, is a neologism no earlier than the 1700’s.
The cults almost certainly arose from Hellenistic Jews and Samaritans trying to synchronize their religious tenets with Gentile philosophy, particularly Platonism. For instance, Philo Judaeus has sometimes been called “proto-Gnostic”.
Though only loosely sharing cosmologies, one feature of all sects now called Gnostic was a single male Ultimate Deity who was often beyond being. Usually, he stood at the head of several beings called Aeons, all of which were directly or indirectly emanations of him and therefore one with him.
The most common designation found for this Ultimate Reality is The One, who was also known as the Monad, the Absolute, Aion Teleos (‘Perfect Aion’), Bythos (‘Depth’), Arke (‘Beginning’), Proarke (‘Before the Beginning’), Propator (‘First Father’), Agennitos Pateras (‘Unbegotten Father’), Afato Gonea (‘Ineffable Parent’), Agnostos Theos (‘Unknown God’), and Arrhetus (‘Unspeakable’). The One is often referred to simply as Theos.
Another feature of nearly all Gnostic schools was that Aeons always came in male and female pairs. Every Aeon had its opposite sex counterpart, even The One, whose counterpart in almost all systems was Sige (‘The Silence’), also known as Charis (‘Grace’), Ennoia (‘Intent’), or Barbelo (‘Forethought’).