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Monotheism: belief in one God
Explicit by c. 540 BC (Second Isaiah)· Belief or practice· Judaism, Christianity & Islam
Mostly agreed by scholarsMost historians agree; some details uncertain.
The belief that only one God exists, held by Jews, Christians, Muslims, Sikhs and others: over half of humanity.
See it on the World Religions map →What it is
Ancient Israel probably moved in stages: worshiping its god Yahweh alongside others, then Yahweh alone without denying other gods (monolatry), then denying that other gods exist at all. The last step is explicit in Second Isaiah, around 540 BC: 'I am the first and the last; besides me there is no god.' Christianity kept one God while teaching the Trinity; Islam stresses tawhid, God's absolute oneness. Sikhism and the Bahá'í Faith are also monotheistic.
Why it matters
It placed all people and history under a single moral authority. Monotheist faiths together count well over 4 billion adherents, more than half the world.
Sources and history
Biblical texts dated by scholars; inscriptions like Kuntillet Ajrud's 'Yahweh and his Asherah' (c. 800 BC) and the Elephantine papyri showing other deities worshiped beside Yahweh.
Questions and debates
When, why and how fast monotheism emerged is debated, as is whether Akhenaten's or Zoroaster's faiths were earlier forms of it.
Connections (7)
▸Akhenaten and worship of the Aten is debated as an early case of Monotheism: belief in one GodDebated by scholars
The connection
Akhenaten worshiped one god, the Aten, and suppressed others, centuries before Israel's prophets. Some call him the first monotheist; Sigmund Freud even suggested Moses learned from him. His Great Hymn to the Aten also resembles Psalm 104. Most scholars, though, see no direct line to Israel's faith.
When and where
Egypt, around 1350 BC. Egyptologist James Henry Breasted hailed him in 1905 as 'the first individual in human history'; Freud's Moses and Monotheism appeared in 1939.
How do we know?
Inscriptions call the Aten 'sole god, like whom there is no other'. Yet Akhenaten himself was worshiped as the god's son and some other deities survived, so the label is contested.
Questions and debates
Whether the hymn's likeness to Psalm 104 reflects borrowing or a shared Near Eastern hymn style is debated, and how Aten ideas could have reached Israel centuries later is unclear.
▸Canaanite religion: El, Baal and Asherah formed the backdrop to Israel's Monotheism: belief in one GodMostly agreed by scholars
The connection
Most scholars now think Israel emerged from within Canaanite culture. Its God absorbed traits and names of El, the father god: the Bible calls God El and Elohim, and 'Israel' itself contains El. Monotheism took shape as Yahweh merged with El while Baal and Asherah were rejected, a long process the Bible tells as apostasy and reform.
When and where
Highlands of Canaan, c. 1200–500 BC; key moments include Elijah's contest with Baal's prophets (in the Bible) and King Josiah's reform around 622 BC.
How do we know?
Ugarit's poetry closely matches biblical language; inscriptions mention 'Yahweh and his Asherah'; early Israelite villages show Canaanite-style pottery and figurines.
Questions and debates
Whether Yahweh began as a southern desert god later merged with El, and how widely Asherah was worshiped beside him, is debated.
▸Monotheism: belief in one God rejected Polytheism: the many gods of the ancient worldHistorical record
The connection
Polytheists added gods easily; monotheism refused. The first commandment forbids other gods, prophets mocked idols as mere wood and stone, and Islam counts shirk, associating partners with God, as the gravest sin. That exclusivity drove conversions, conflicts and temple closures across the Roman world and beyond.
When and where
Israel and Judah, c. 800–500 BC; the Roman Empire, where Christian emperors banned pagan sacrifice by 391; Mecca, where Muhammad cleared the Kaaba's idols in 630.
Historical evidence
Scripture states it directly, as in Isaiah 44 and Quran 112; Roman laws in the Theodosian Code; archaeology of temples closed or converted into churches.
Questions and debates
How sharp the break really was: some scholars argue saints, angels and local shrines took over roles once held by many gods; others reject the comparison.
▸Zoroastrianism may have influenced Monotheism: belief in one GodDebated by scholars
The connection
Judeans lived under Persian rule from 539 BC, and Isaiah hails Cyrus as God's anointed. Ideas prominent in Zoroastrianism, a supreme good God opposed by an evil adversary, angels, resurrection and final judgment, become clear in Jewish texts from then on and passed into Christianity and Islam.
When and where
The Persian Empire, 539–330 BC, especially Babylon and Persian-ruled Judah (Yehud); later contact under the Parthians.
How do we know?
Timing and parallels only; no text records borrowing. Late biblical books such as Zechariah, Job and Daniel show new ideas of Satan, angels and resurrection.
Questions and debates
Some scholars see strong influence; others say the ideas grew within Judaism and that Zoroastrian texts were written down too late to prove which came first.
▸Islam teaches strict Monotheism: belief in one GodHistorical record
The connection
Islam's central doctrine is tawhid, God's absolute oneness. The short sura 112 declares God 'One, eternal, neither begetting nor begotten, with none like Him.' Associating anything with God (shirk) is the gravest sin. That is why Islam rejects the Christian Trinity and keeps images out of worship.
When and where
Preached by Muhammad from about 610 in Mecca, then a polytheist city whose Kaaba held many idols, which he removed in 630.
Historical evidence
The Quran itself, the shahada recited daily, and the Dome of the Rock's inscriptions of 691/692, which quote sura 112.
Questions and debates
Scholars debate how far pre-Islamic Arabs already knew a high god, Allah, above lesser deities, and who the hanifs, Arabs said to worship one God, really were.
▸Council of Nicaea and the Nicene Creed affirmed Christ's divinity within Monotheism: belief in one GodHistorical record
The connection
Christians inherited Judaism's insistence on one God but also worshipped Jesus. Arius eased the tension by making the Son a lesser, created being. Nicaea instead declared the Son 'of one substance' with the Father: one God, not two. This opened the way to the doctrine of the Trinity, one God in three persons, defined more fully in 381.
When and where
Nicaea, in Asia Minor, AD 325; Bishop Alexander of Alexandria and his deacon Athanasius led opposition to Arius. The Council of Constantinople in 381 extended the creed to the Holy Spirit.
Historical evidence
The creed's text survives, opening 'We believe in one God'; contemporary letters and church histories record the debate and its outcome.
Questions and debates
Jews and Muslims hold that the Trinity compromises strict monotheism; Christians maintain it is monotheism. Unitarians and some other groups also reject it.
▸Hebrew prophets: Amos, Isaiah, Jeremiah championed Monotheism: belief in one GodMostly agreed by scholars
The connection
The prophets demanded that Israel worship its God alone, attacking Baal, Asherah and idols. Over about two centuries their message sharpened from loyalty to one God among many to the claim that no other god exists. Second Isaiah, writing in exile around 540 BC, states it outright: 'besides me there is no god.'
When and where
Israel and Judah, c. 760–586 BC (Amos, Hosea, Isaiah, Jeremiah), then Babylon around 540 BC (Second Isaiah).
How do we know?
Their own books, edited by later followers; the progression from Hosea's demand for loyalty to Isaiah 44–45's denial of other gods is visible in the texts.
Questions and debates
Whether the prophets were a minority later made the nation's voice, and how much later editors sharpened their monotheism, are debated.