I am utterly amazed, utterly enchanted! I have a precursor, and what a precursor! I hardly knew Spinoza: that I should have turned to him just now, was inspired by “instinct.” Not only is his overtendency like mine—namely to make all knowledge the most powerful affect—but in five main points of his doctrine I recognize myself; this most unusual and loneliest thinker is closest to me precisely in these matters: he denies the freedom of the will, teleology, the moral world-order, the unegoistic, and evil. Even though the divergencies are admittedly tremendous, they are due more to the difference in time, culture, and science. In summa: my lonesomeness, which, as on very high mountains, often made it hard for me to breathe and make my blood rush out, is now at least a twosomeness. Strange!
Among the boldest elements of Spinoza’s philosophy is his conception of God. Spinoza’s God, as presented in the Ethics, is a far cry from the traditional God of the Abrahamic religions. What Spinoza calls “God or Nature” (Deus sive Natura) lacks all of the psychological and ethical attributes of a providential deity. His God is not some personal agent endowed with will and understanding and even emotions, capable of having preferences and making informed choices. Spinoza’s God does not formulate plans, issue commands, have expectations, or make judgments. Neither does Spinoza’s God possess anything like moral character. His God is neither good nor wise nor just. It is a category mistake to think of God in normative or value terms. What God is, for Spinoza, is Nature itself—the infinite, eternal, and necessarily existing substance of the universe. God or Nature just is; and whatever else is, is “in” or a part of God or Nature. Put another way, there is only Nature and its power; and everything that happens, happens in and by Nature. There is no transcendent or even immanent supernatural deity; there is nothing whatsoever outside of or distinct from Nature and independent of its processes.
...Perhaps the most deleterious superstition of all is the belief in the immortality of the soul. Like the notion of a providential God, the idea that a person will experience a postmortem existence in some world-to-come is a part of all three Abrahamic religions. While there is, of course, much diversity among the major faiths about what exactly happens to a person when he dies, and while Judaism, at least, generally does not make the belief in immortality a necessary tenet of the faith, the eternal fate of the soul was of the utmost importance to the great majority of Spinoza’s contemporaries, and this is what he found so troubling. In his view, a robust doctrine of personal immortality, like the eschatology that accompanies it, only strengthens those harmful passions that undermine the life of reason. He devotes a good deal of the final part of his Ethics to showing that while there is, in a sense, an eternal part of the human mind that remains after a person’s death—namely, the knowledge and ideas that she has acquired in this lifetime—there is nothing personal about it. When you are dead, Spinoza is saying, you are dead.