The pertinent excerpt:
The chapter on Spinoza is of particular interest. The article on Spinoza in Bayle's Dictionary is longest of all, and it is clear that Spinoza held a unique fascination for him, even to the point of serving as an alter ego. Even so, Bayle is unrelentingly critical of Spinoza's metaphysics, especially of what he called the "abominable hypothesis" that there is but one substance, which is God. Bayle's actual arguments against this pantheistic substance monism have not been taken very seriously by commentators, however, and a great virtue of Ryan's book is to demonstrate that "Bayle's reading of Book I of the Ethics shows a good deal more subtlety than has been commonly allowed" (p.136).
Ryan distinguishes five objections in Bayle's treatment of Spinoza: (1) the argument from compositeness of extension: substance monism is incompatible with substance having extension as an attribute, which consists of real parts, which are beings per se and as such substances themselves; (2) the argument from incompatible properties that the single substance would have; (3) the argument from mutability that follows from the separability of the parts of extension; (4) the argument from the identity of attributes based on the real identity of attributes with substance; (5) the argument from divine goodness that God as the only subject of predication would be the author of evil, would struggle against himself, etc.