Not all philosophers agree with Aquinas. René Descartes, for example, believed that God could do absolutely anything, even the logically impossible, such as draw a round square. But even if we accept, for the sake of argument, Aquinas’ explanation, there are other problems to contend with. For example, can God create a world in which evil does not exist? This does appear to be logically possible. Presumably God could have created such a world without contradiction. It evidently would be a world very different from the one we currently inhabit, but a possible world all the same. Indeed, if God is morally perfect, it is difficult to see why he wouldn’t have created such a world. So why didn’t He?

The standard defense is that evil is necessary for free will. According to the well-known Christian philosopher Alvin Plantinga, “To create creatures capable of moral good, [God] must create creatures capable of moral evil; and He can’t give these creatures the freedom to perform evil and at the same time prevent them from doing so.” However, this does not explain so-called physical evil (suffering) caused by nonhuman causes (famines, earthquakes, etc.). Nor does it explain, as Charles Darwin noticed, why there should be so much pain and suffering among the animal kingdom: “A being so powerful and so full of knowledge as a God who could create the universe, is to our finite minds omnipotent and omniscient, and it revolts our understanding to suppose that his benevolence is not unbounded, for what advantage can there be in the sufferings of millions of the lower animals throughout almost endless time?”

What about God’s infinite knowledge — His omniscience? Philosophically, this presents us with no less of a conundrum. Leaving aside the highly implausible idea that God knows all the facts in the universe, no matter how trivial or useless (Saint Jerome thought it was beneath the dignity of God to concern Himself with such base questions as how many fleas are born or die every moment), if God knows all there is to know, then He knows at least as much as we know. But if He knows what we know, then this would appear to detract from His perfection. Why?

There are some things that we know that, if they were also known to God, would automatically make Him a sinner, which of course is in contradiction with the concept of God. As the late American philosopher Michael Martin has already pointed out, if God knows all that is knowable, then God must know things that we do, like lust and envy. But one cannot know lust and envy unless one has experienced them. But to have had feelings of lust and envy is to have sinned, in which case God cannot be morally perfect.

What about malice? Could God know what malice is like and still retain His divine goodness? The 19-century German pessimist Arthur Schopenhauer was perhaps the first philosopher to draw attention to what he called the “diabolical” in his work “On Human Nature”:

For man is the only animal which causes pain to others without any further purpose than just to cause it. Other animals never do it except to satisfy their hunger, or in the rage of combat …. No animal ever torments another for the mere purpose of tormenting, but man does it, and it is this that constitutes the diabolical feature in his character which is so much worse than the merely animal.

It might be argued, of course, that this is precisely what distinguishes humans from God. Human beings are inherently sinful whereas God is morally perfect. But if God knows everything, then God must know at least as much as human beings do. And if human beings know what it is like to want to inflict pain on others for pleasure’s sake, without any other benefit, then so does God. But to say that God knows what it is like to want to inflict pain on others is to say that God is capable of malicious enjoyment.