The oldest riddle for believers: if God is good, why is there evil?

Around 300 BCE, Epicurus is said to have posed a puzzle that still keeps philosophers and theologians up at night. It's called the problem of evil, and it targets a very specific idea of God: one who is all-powerful, all-knowing, and perfectly good. If such a being exists, why is the world full of suffering — earthquakes, disease, cruelty? An all-powerful God could prevent it, an all-good God would want to, and an all-knowing God would know how. Yet evil persists.

The sharpest version is the logical problem of evil: it claims these traits and the existence of evil are flatly contradictory, like a square circle. A softer version, the evidential problem of evil, is more modest — it argues that the sheer amount of pointless suffering makes God's existence unlikely, without claiming outright impossibility.

Replies to the puzzle are called theodicies — attempts to justify God's ways. The most famous is the free-will defense: genuine moral goodness requires free creatures who can also choose evil, so a world with freedom is worth the risk. Others argue suffering builds character ("soul-making") or that finite minds can't judge an infinite plan. Critics push back: what about the agony of animals in the wild, long before any human free will was on the scene?

What makes this a great piece of philosophy isn't picking a winner — it's how a single clean argument forces you to make your concepts precise. What exactly do we mean by good, by power, by evil?