Spinoza appealed to a version of PSR that has both a positive and negative component:
Spinoza's Principle of Sufficient Reason (PSR): every fact that obtains has a complete explanation for why it obtains, and every fact that fails to obtain has a complete explanation for why it fails to obtain.
Suppose you accept Spinoza's PSR. Then you have a reason to think that every possible world is, and must be, actual. Otherwise, you will be hard pressed to find an explanation for why some possibilities fail to obtain. But if so, then there is an under-appreciated rational explanation for why the universe exists, rather than nothing. It is also an under-appreciated rational explanation for why our universe exists, rather than another. In this way, Spinoza's PSR provides the materials for a cosmological argument for naturalism.
Spinoza has been making a comeback in recent decades in the study of early modern philosophy. Here's at least one reason why philosophers of religion should celebrate this.