A world of many unities

By the third and fourth centuries CE, the Mediterranean world had become a laboratory of the One. From Britain to Persia, competing creeds and philosophies claimed to disclose the single principle behind all things. The pagan philosopher might speak of the Logos or the One of Plotinus; the Christian of the Trinity; the Jew of the Name; and, soon, the Muslim of Allah. What differed were not the aspirations but the idioms.

This plurality of monotheisms arose in an age of empire, a world seeking coherence across vast diversity. Political unification under Rome demanded a theological counterpart. The old city gods seemed parochial; a universal order required a universal deity. From this need for common meaning, the religions of the Book found their momentum.

Judaism after empire

For Judaism, the destruction of the Second Temple in 70 CE was both disaster and transformation. Deprived of sacrifice, Jewish life reorganized around text, prayer, and law. The rabbis who compiled the Mishnah and later the Talmud turned covenant into a portable institution: holiness no longer required a shrine but obedience to Torah. This intellectualization of worship made Judaism uniquely adaptable.

Yet it also sharpened its boundary with the Hellenistic world. The rabbinic insistence on divine unity, “the Lord is One”, was not philosophical but ethical, a rejection of imperial and metaphysical hierarchy alike. In late antiquity, to be monotheist was an act of cultural resistance: fidelity to law rather than curiosity about being.

Christianity and empire

Christianity’s trajectory was opposite. Born within Judaism, it expanded by translating the Hebrew God into the universal savior of the Greco-Roman world. When Constantine legalized the faith in 313 CE and Theodosius later made it official, monotheism became imperial ideology.

The conversion of the empire reshaped both. The Church inherited Rome’s administrative genius and, with it, a taste for orthodoxy: one empire, one emperor, one God. Councils at Nicaea and Chalcedon codified doctrine in the same spirit as Roman law. The Trinity, paradoxically, became the formula of unity, difference harmonized within substance. In theology as in politics, diversity was tolerated only within a single order.

The new revelation

Into this already monotheistic world came Islam. The Qur’an addressed a landscape of sects and schisms with a single, radical affirmation: “Say, He is God, One.” (112:1). Where Christianity had reconciled unity with incarnation, Islam restored absolute simplicity. God has no partners, no intermediaries, no images.

This austerity was not philosophical minimalism but moral protest, a return to purity against theological complexity. Yet Islam also inherited the intellectual instruments of the world it superseded: Greek logic through Syria, biblical narrative through late antique Judaism and Christianity, and the imperial ideal of universal law. The result was a new civilization in which revelation and reason, faith and empire, fused once again.

Shared inheritances

Despite their conflicts, the three faiths of late antiquity shared assumptions deeper than doctrine:

• Scripture as revelation written;

• Law as the expression of divine will;

• History as the theatre of meaning;

• Unity as the measure of truth.

Each positioned itself as the fulfilment of the others: Christianity as the true Israel, Islam as the final correction, rabbinic Judaism as the guardian of the original covenant. Their rivalries were, in essence, arguments about interpretation, about which version of oneness would define the world.

The intellectual climate

Philosophy did not die with paganism; it migrated into theology. Neoplatonism, with its hierarchy from the ineffable One to the material world, offered a conceptual map for divine transcendence. Christian mystics, Jewish thinkers like the early Merkabah visionaries, and Muslim philosophers alike drew on its vocabulary. Late antiquity thus became the hinge between ancient metaphysics and medieval rationalism, a world still enchanted, yet already logical.

Continuity through contention

Seen from a distance, the period between the third and eighth centuries is less a succession of revelations than a continuing conversation about the nature of unity. Judaism preserved the ethical kernel of monotheism; Christianity universalized it through incarnation and reason; Islam restored its simplicity and global scope. Each tradition carried the question of the One into new social and intellectual terrain.

Together they established the framework within which medieval philosophy, Jewish, Islamic, and Christian alike, would operate: the assumption that truth is singular, that the world is intelligible, and that reason is itself a reflection of the divine.

Reflection

To a modern, secular eye, the drama of late antiquity reads as a vast exercise in the humanization of abstraction. Each faith sought to embody the ineffable: in law, in person, in book. What unites them is not theology but anthropology, the human drive to see the world as coherent, to imagine meaning large enough for empire and intimate enough for conscience.

The Mediterranean of late antiquity did not resolve the question of the One; it globalized it. The centuries that followed would turn those rival revelations into philosophy, and philosophy into the search for reason itself.