If God Is Good and All-Powerful, Why Is There So Much Evil?
The oldest objection to belief in God is still the strongest felt. The tradition has an answer, but it is not the one most people expect, and it does not pretend to explain every particular suffering.
The Objection
If God were wholly good, he would want to prevent evil. If he were all-powerful, he could. Yet children die of cancer, earthquakes bury cities, and human beings do unspeakable things to one another. Either God is not good, or he is not all-powerful, or he does not exist. And even if some evil could be justified, the sheer amount of it, much of it falling on the innocent and serving no visible purpose, makes a good God very hard to believe in.
Aquinas did not hide from this. When he set out to ask whether God exists, the very first objection he raised against himself was this one: if one of two contraries were infinite, the other would be destroyed altogether; God is infinite goodness; so if God existed, there would be no evil (Summa Theologiae I, q. 2, a. 3, obj. 1). The answer he gave in reply to that objection is the backbone of everything that follows.
Two Versions of the Problem
Philosophers now separate two forms of the argument.
The logical problem claims that God and evil are flatly incompatible, so that believing in both is a contradiction. Most philosophers of religion, including many atheists, now accept that this version fails. To defeat it, one need only show that it is possible for a good and omnipotent God to have a morally sufficient reason for permitting evil, even if we cannot say what that reason is. Since the 1970s, largely through Alvin Plantinga’s free-will defence, it has been widely granted that this can be shown.
The evidential problem is more modest and more serious. It grants that God and evil may be compatible, but argues that the amount and kind of evil we see, especially suffering that seems to serve no purpose at all, makes God’s existence improbable. This is the version most people actually feel, and it is the one that needs answering.
What Evil Is
The tradition begins with a claim about what evil is. Following Augustine, Aquinas holds that evil is not a thing in its own right, but a privation: the absence of a good that ought to be there (I, q. 48, a. 1). Blindness is not a substance; it is the lack of sight in a being that should see. Cruelty is not a positive power; it is a will failing to be what a will should be.
This is not a word game that makes suffering unreal. Blindness is entirely real, and so is pain. The point is that evil is always parasitic on good. It exists only in good things, as a defect in them, and it cannot exist on its own. So God, in creating, creates only good things. He does not make evil as he makes a tree or a man.
What God Causes and What He Permits
From this the tradition draws a distinction between two kinds of evil (I, q. 48, a. 5; q. 49, a. 2).
Moral evil, sin, is the defect of a free will turning away from the good. God is in no way its cause. He creates and sustains the will and its power to act, but the failure in a sinful act comes from the creature alone. God permits it because he has made creatures who are genuinely free, and a freedom that could never be misused would not be the freedom to love.
Physical evil, such as disease, decay, natural disaster or death, belongs to a material world of things that act according to their natures and can therefore fail, wear out, and collide. Aquinas argues that a universe containing only things that can never fail would be a lesser universe, not a better one (I, q. 48, a. 2). The fire that warms also burns; the tectonic movement that builds continents also levels towns. Scripture adds that creation itself was caught up in the consequences of the Fall and “subjected to futility”, waiting to be “set free from its bondage to decay” (Romans 8:20–21).
The Greater Good
Here is the reply Aquinas gave to his own first objection. Quoting Augustine, he says that God, being the highest good, would not permit any evil in his works unless he were so good and so powerful as to bring good even out of evil (I, q. 2, a. 3, ad 1). The Catechism makes the same point with the story of Joseph, whose brothers sold him into slavery: “You meant evil against me; but God meant it for good” (Genesis 50:20; CCC 312).
The supreme case is the Cross. The worst act human beings have ever committed, the murder of the innocent Son of God, became the means of the world’s redemption. That does not make the crime good. It shows that no evil is beyond God’s power to turn to good.
God causes no moral evil and creates no evil as a thing. He permits evil, in free creatures and in a world of things that can fail, because he is able to bring from it a good greater than the good of preventing it. The claim is that such a good exists, not that we can always see it.
What the Answer Does Not Claim
The last clause matters. The tradition does not claim to know why this child suffered or why this city was destroyed. The Catechism says plainly that no quick answer will do, and that only the Christian faith as a whole answers the question of evil (CCC 309).
The Book of Job is the scriptural warning against pretending otherwise. Job’s friends had a tidy explanation for his suffering, and God rebukes them for it (Job 42:7). Job is answered not with an explanation but with a question: “Where were you when I laid the foundation of the earth?” (Job 38:4). That is not a refusal to engage. It points out how limited our vantage point is. If God exists and governs a universe across all of time and eternity, it is no surprise that we cannot see the purpose of every part of it from where we stand. Philosophers call this “sceptical theism”, and it is a direct reply to the evidential argument. Our failing to see a reason for an evil is not good evidence that there is none.
Nor does the Christian answer end with an argument. God did not explain suffering from a distance; in Christ he entered into it. And the faith looks to an end in which suffering is not just explained but undone: “I consider that the sufferings of this present time are not worth comparing with the glory that is to be revealed to us” (Romans 8:18).
Common Replies
”Couldn’t God have made free creatures who always choose the good?”
This is the strongest reply, and Catholics should feel its force, because the Church teaches that the saints in heaven are free and yet cannot sin. The traditional answer is that the saints reach that state through a freedom first exercised under trial. A love that has never been free to refuse is not the same as a love that has chosen. God could have created beings already fixed in the good, and arguably the angels who did not fall were given a single decisive choice. But God also willed to share with his creatures the dignity of becoming, by their own free choices, what they are meant to be (CCC 306–308). Whether that good is worth its cost is exactly what the objection disputes. The Catholic answer is that God, who sees the whole, judged that it is.
”What about suffering no one chose, like animal pain and natural disasters?”
Free will does not explain these directly, which is why the tradition does not rest on free will alone. It appeals to the goodness of a material world governed by stable natures, which by its very nature includes generation and corruption. It also appeals to the disorder the Fall introduced into creation, and to the limits of our vantage point. None of these makes such suffering less terrible. They show only that its existence does not prove there is no God.
”Isn’t ‘greater good’ talk callous to people who are suffering?”
It can be, if it is offered as a pat answer to a grieving person. That is the mistake Job’s friends made. The philosophical question (is belief in God reasonable given evil?) and the pastoral one (how do I bear this?) are different questions. The first calls for arguments like the ones above. The second calls first for presence, prayer and silence, and then for the Cross, which shows a God who does not stand apart from suffering.
”Why believe in God at all, then?”
The problem of evil is one consideration, and a weighty one. But it has to be set beside the reasons for believing that God exists, which do not depend on the world being free of suffering. See Can God’s Existence Be Proven, or Is It Faith Alone? If those reasons are sound, the question is no longer whether there is a God despite evil, but why a God who exists permits it. That question is hard, but it is not unanswerable.