Philosophically, Spinoza is a monist or pantheist. He believes that there is only one entity in the universe, that is, the universe itself is a whole, and "God" and the universe are the same thing. His conclusion is based on a set of definitions and axioms, and is drawn by logical reasoning. "Spinoza's God" includes not only the material world, but also the spiritual world. Spinoza also believes that "God" is the "internal cause" of everything, and "God" dominates the world through "natural laws", so everything that happens in the material world has its inevitability; Only "God" in the world is completely free. Although people can try to get rid of external constraints, they will never get free will. If we can see things as inevitable, then the easier it is for us to become one with God. Therefore, Spinoza suggested that we should look at things "in the eternal stage".

In ethics, Spinoza believes that as long as a person is influenced by the outside world, he is in a state of slavery, and as long as he agrees with God, he will no longer be influenced by this, but will gain relative freedom and get rid of fear. Spinoza also believes that ignorance is the root of all evil. On the issue of death, Spinoza's famous saying is: "A free man at least thinks of death, and his wisdom is not a meditation on death, but a meditation on life."

Spinoza is a thorough determinist, and he thinks that all the things that have happened are absolutely inevitable.