Baruch Spinoza (1632–1677) believed in pantheism, meaning that God is present in all things. It is believed that the ancient Druids were pantheists of a sort. So, too, is the contemporary New Age tree hugger. It is a form of nature worship that naturally made him suspect by the then all-seeing eyes of the Christian authorities. The fact that he was also raised as an Orthodox Jew did not endear him to the Church authorities, either. The Jewish leaders cast him out for his pantheistic beliefs as well, so Spinoza was a man without an organized religion.

Like Descartes, Spinoza wrestled with the idea of Substance.

Descartes called the infinite substance God; Spinoza called it Nature. His belief that God is Nature and that nature is one substance that can shape-shift into various forms that he called modes is not unlike the Monist philosophies of the Presocratics.

Like Descartes, Spinoza eschewed the passions, believing that they got in the way of inner peace. He believed in acceptance of your lot in life, and that you are part (however inconsequential) of a cosmic Big Picture (however impersonal), and that you are a happy anonymous mode among a myriad of other modes should provide at least a modicum of serenity. Needless to say, many disagreed with this philosophy.