Baruch Spinoza: The Radical Thinker Who Redefined God and Got Kicked Out for It

The Most Dangerous Jew in Europe

In the summer of 1656, the leaders of Amsterdam’s Portuguese Jewish community gathered to pronounce one of the harshest excommunications in Jewish history. The target was a twenty-three-year-old man named Baruch Spinoza — brilliant, quiet, and already thinking thoughts that would terrify rabbis, priests, and kings for centuries to come.

The cherem — the formal ban — did not mince words. It cursed him “by day and by night, in his sleeping and in his waking.” It declared that no one should communicate with him, read anything he wrote, or come within four cubits of him. It was, by the standards of any religious community in any era, total social annihilation.

Spinoza walked away, changed his first name from Baruch (Hebrew for “blessed”) to Benedict (the Latin equivalent), and spent the next twenty years quietly building a philosophical system that would help lay the foundations of modern democracy, biblical criticism, and secular thought.

The Portuguese Jews of Amsterdam

To understand Spinoza, you have to understand where he came from.

His family were Sephardic Jews — descendants of the Jews expelled from Spain and Portugal in the 1490s. Many of these families had been forced to convert to Christianity (becoming conversos or marranos) but secretly maintained Jewish practices for generations. When they arrived in Amsterdam — a city known for relative religious tolerance — they could finally live openly as Jews.

The Amsterdam Portuguese Jewish community was proud, prosperous, and intensely self-conscious. These were people who had survived the Inquisition. They had built a magnificent synagogue (the Esnoga, still standing today). They were deeply invested in maintaining their hard-won Jewish identity. They were not about to let a young man with dangerous ideas threaten everything they had built.

Baruch de Spinoza was born on November 24, 1632, into this world. His father, Michael, was a successful merchant. Baruch received a traditional Jewish education, studying Torah, Talmud, and Hebrew. He was a gifted student. His teachers expected great things.

They got great things. Just not the kind they expected.

The Making of a Heretic

What exactly led Spinoza to his radical conclusions? The path was gradual. He studied not just Jewish texts but also Latin, mathematics, and the new philosophy of René Descartes. He read widely in science and began to apply rational analysis to questions that had traditionally been answered by faith and authority.

Several ideas began to crystallize — ideas that placed him on a collision course with every religious establishment in Europe:

The Torah is a human document. Spinoza argued that the Five Books of Moses were not dictated by God but compiled by human editors over time. He pointed to internal contradictions, anachronisms, and stylistic variations as evidence. This made him one of the earliest practitioners of what would later be called biblical criticism — roughly two centuries before it became mainstream scholarship.

God is not a person. The God of Spinoza does not think, will, love, or judge. God does not answer prayers. God does not choose peoples or reveal commandments. God is the infinite substance of reality itself — what Spinoza famously called Deus sive Natura (God or Nature). Everything that exists is an expression of this single, unified substance.

There is no free will. Human beings, like everything else in nature, operate according to causes and effects. We feel free because we are aware of our desires but not of the causes that produce them. Understanding this, Spinoza believed, was the key to genuine freedom — not the freedom to choose otherwise, but the freedom that comes from understanding why you do what you do.

The Cherem

The excommunication of July 27, 1656, was dramatic and absolute. The text of the cherem has survived:

“By the decree of the Angels and the judgment of the Saints, we excommunicate, cut off, curse, and anathematize Baruch de Espinoza… cursed be he by day and cursed by night; cursed when he lies down and cursed when he rises up.”

The ban was unusual in its severity. Most cheremot were temporary — a slap on the wrist, a cooling-off period. Spinoza’s was permanent. And unlike many who were excommunicated, he never sought reinstatement. He simply left.

Why was the community so harsh? Several factors were at play. The Amsterdam Jews were vulnerable — guests in a Christian country, dependent on Dutch tolerance. A Jew publicly questioning the divine origin of Scripture could provoke a backlash against the entire community. There were also political dynamics within the community itself, power struggles that made an example of the young freethinker convenient.

But the simplest explanation may be the most accurate: Spinoza’s ideas were genuinely dangerous. If God is Nature, then the entire structure of revealed religion — commandments, covenant, chosenness, prayer — collapses. The rabbis understood the implications, even if Spinoza had not yet published a word.

The Lens Grinder

After the excommunication, Spinoza settled into a quiet life. He moved to Rijnsburg, then to Voorburg, and finally to The Hague. He supported himself by grinding lenses for microscopes and telescopes — a skilled craft that connected to the scientific revolution transforming European thought.

He lived simply. He rented modest rooms. He ate little. He corresponded with some of the finest minds in Europe — including the scientist Christiaan Huygens, the philosopher Gottfried Leibniz, and the secretary of the Royal Society, Henry Oldenburg. He was offered a prestigious chair at the University of Heidelberg and turned it down, fearing that academic obligations would compromise his freedom to think and write as he pleased.

His daily life had a monastic quality: grinding lenses by day, writing philosophy by night, receiving visitors who came to discuss ideas. He was, by all accounts, gentle, generous, and utterly indifferent to wealth, fame, or comfort.

The Ethics

Spinoza’s masterpiece, the Ethics (Ethica Ordine Geometrico Demonstrata), was written over many years and published only after his death. It is one of the strangest and most powerful works in the history of philosophy.

The book is structured like a geometry textbook — definitions, axioms, propositions, proofs, and corollaries. This was deliberate. Spinoza believed that philosophical truths could be demonstrated with the same certainty as mathematical theorems. The form is forbidding. The content is revolutionary.

The Ethics moves through five parts: on God (substance), on the mind, on the emotions, on human bondage (how we are enslaved by our passions), and on human freedom (how understanding liberates us). Its central argument is that everything in the universe — rocks, rivers, human minds, galaxies — is an expression of a single infinite substance, which can be called God or Nature.

The practical upshot is radical: freedom comes through understanding. Most people are driven by passions they do not comprehend — fear, desire, jealousy, ambition. The path to freedom is not willpower but knowledge. When you understand why you feel what you feel, the passion loses its grip. You move from being acted upon to acting — from bondage to freedom.

The Father of the Enlightenment

Spinoza’s influence on subsequent thought is almost impossible to overstate. He is sometimes called the father of the Enlightenment — the intellectual movement that championed reason, tolerance, and individual rights.

His arguments for the separation of church and state (laid out in the Theologico-Political Treatise of 1670) directly influenced the development of liberal democracy. His insistence that Scripture be read as a historical document, not a divine dictation, opened the door to modern biblical scholarship. His metaphysics — the idea that mind and body are two aspects of a single reality — anticipated developments in neuroscience and philosophy of mind.

Hegel called him “the most important philosopher of the modern era.” Einstein, when asked if he believed in God, replied: “I believe in Spinoza’s God.” Goethe, Nietzsche, George Eliot, Borges — the list of thinkers who found in Spinoza a kindred spirit stretches across centuries.

The Jewish Question

Spinoza’s relationship with Judaism is complicated and, for many Jews, painful. He was not merely a dissenter within Judaism; he left Judaism entirely. He did not join another religion — he was not a Christian convert — but neither did he remain a Jew in any recognizable sense. He is, in some ways, the first secular Jew: someone shaped by Jewish culture and texts but living entirely outside Jewish communal life.

For centuries, the Jewish world did not know what to do with him. Was he a traitor? A prophet? A cautionary tale? In the nineteenth century, the Jewish Enlightenment movement (Haskalah) embraced him as a hero — a Jew who had championed reason over dogma. In the twentieth century, David Ben-Gurion, Israel’s first prime minister, publicly called for the cherem to be revoked (the Amsterdam community declined). Today, Spinoza is taught in Israeli universities and debated in Jewish philosophical circles.

He remains a paradox: a thinker expelled from Judaism who became, in some sense, one of its most important products.

Death and Legacy

Spinoza died on February 21, 1677, at the age of forty-four. The likely cause was lung disease, probably exacerbated by years of inhaling glass dust from his lens-grinding work. He died in his rented room in The Hague, among his books and lenses.

His friends immediately arranged for the publication of his unpublished works, including the Ethics. The books were banned almost everywhere — by the Catholic Church, by the Dutch Reformed Church, by Jewish authorities. They were read anyway, passed from hand to hand, discussed in secret, and gradually absorbed into the mainstream of Western thought.

Today, Spinoza’s face appears on Dutch stamps and currency. His statue stands in Amsterdam, not far from the synagogue that expelled him. His ideas — that God is Nature, that freedom comes through understanding, that Scripture is a human document, that church and state must be separate — are so embedded in modern Western thought that we forget how radical they once were.

A lens grinder from Amsterdam, excommunicated at twenty-three, who saw more clearly than almost anyone in history. That was Spinoza.