This essay presents Mendelssohn's neglected vindication of theism through a refutation of Spinoza's philosophy in the Morgenstunden and highlights its relevance for discussions in contemporary philosophy of religion by (i) contextualizing Mendelssohn's argument within the reception of Spinoza's philosophy at the dawn of the 18th century, (ii) tracing the path of Mendelssohn's argument from Spinoza's philosophy to theism, (iii) and applying Mendelssohn's argument to Linda Zagzebski's account of divine omniscience showing that her account is not only incoherent but also undermines (...) the theistic assumption that the world has an existence outside of God. (shrink)