Spnoza approached mysticism through the clear path of logic. If you read the Mool Mantar (basic premise) in Sri Guru Granth Sahib, it co-relates closely with the concept of God Nature put forth by Spinoza. One, True, Prime Cause, Non-interfering, Non-moved, Eternal, viewing himself through himself, self-born, having infinite attributes of which we can comprehend a few (two). Further, even the concept of transmigration of the understanding arrived by mind, oneness of all creatures, --- so many similarities, had his writings been known they would have been incorporated in the SGGS (imho only) or maybe his writings should be read as prelude to SGGS.
