Why was Spinoza widely denounced as an atheist after his death?

Benedict de Spinoza was widely denounced as an atheist for nearly a century after his death primarily because his philosophical system was entirely severed from traditional religious and historical perspectives. His strong opposition to any form of supernaturalism led many contemporaries to misunderstand his work.1

The perception of his atheism was solidified by the French philosopher Pierre Bayle, who asserted in his Dictionnaire historique et critique (1697) that Spinoza was the first philosopher to transform atheism into a formal system. This reputation was further fueled by the publication of his Tractatus Theologico-Politicus (1670), which was officially banned in the Netherlands for its rejection of the historical accuracy of the Bible, the reality of miracles, and the validity of ancient ceremonial laws.123

While Spinoza’s philosophy is now recognized as a form of pantheism—where God is identified with the infinite substance of the universe—his contemporaries viewed his rejection of a personal, transcendent deity as a denial of God altogether. It was not until the late 18th century that thinkers like Novalis began to offer a more nuanced assessment, describing him as a "God-intoxicated man".124