Spinoza published the Tractatus Theologico-Politicus anonymously in 1670, fourteen years after his excommunication, arguing at length that religious and political authority ought to be kept strictly separate and that the Bible should be read and interpreted using the same historical and philological methods scholars applied to any other ancient text, rather than being treated as immune from ordinary critical inquiry. He argued that biblical accounts of miracles and supernatural events could generally be explained through natural causes combined with the limited understanding of the people who originally reported them, treating scripture as a human document shaped by specific historical circumstances rather than a direct, unmediated transmission of divine truth.
The book caused immediate scandal, was formally banned in the Dutch Republic within a few years of publication, and is regarded by historians of philosophy, including Steven Nadler, as one of the founding texts of both modern secular biblical criticism and modern liberal political theory, arguing for freedom of thought and expression on explicitly philosophical rather than merely tactical grounds. Spinoza's broader philosophical system, most fully developed in his posthumously published Ethics, identified God with Nature itself, a form of pantheism that placed him, alongside his excommunication and his Tractatus, among the most consequential and controversial religious thinkers of the early modern period.