Some people claim the existence of God cannot be falsified. As I have argued elsewhere, this is not true. One way to falsify God’s existence is to show that the concept of God is logically incoherent. This can be done by demonstrating that two or more supposed divine attributes are logically incompatible. For example, it has been argued that omnipotence and omnibenevolence are logically incompatible.
The argument is set forth along these lines: Omnipotence entails the power to actualize any state of affairs that is logically possible to actualize. There is nothing logically incoherent about an omnipotent being committing evil, so omnipotence must include the power to actualize a world in which the omnipotent being commits evil. As an omnibenevolent being, however, God is incapable of committing evil. Therefore, God cannot be omnipotent. While a being can be either omnibenevolent or omnipotent, no being can be both omnibenevolent and omnipotent. Since the theistic concept of God entails both, the God of theism cannot exist.
Areas of agreement
How might the theist respond to this objection? Let us start with some points of agreement. First, we agree that God must be both omnipotent and omnibenevolent. Theistic philosophers have long held that the concept of God is that of the greatest conceivable being (GCB). God is a being of which a greater cannot be conceived. If we can conceive of some being Y who is greater than the being we call God, then being Y is the true God. Since it is greater to be all-powerful than partially powerful, the GCB must possess the property of being all-powerful. Likewise, since it is greater to be all-good than partially good, the GCB must possess the property of being all-good.