This essay examines a conflict between God's omnipotence and His omniscience. I discuss our intuitions regarding omnipotence and omniscience and describe a method by which we can decide whether a being is omnipotent. I consider the most promising versions of omnipotence and argue that they produce a genuine conflict with omniscience. Finally, I suggest that we can take the example of omniscience and generalize it to several of God's essential properties and thereby reveal incompatibilities that result even from sophisticated conceptions of divine attributes.