Arguments Against the Existence of God
Does Suffering Challenge Belief in God?
If God is all-powerful, all-knowing, and entirely good, why does suffering exist? This question — known as the problem of evil — is one of the oldest and most persistent arguments against the existence of God. Alongside it, the findings of modern science have been used to argue that a creator God is unnecessary. Together, these represent the most serious challenges that believers must respond to. This lesson examines both challenges and the responses that religious traditions offer.
Types of Evil and Suffering
Philosophers distinguish two types of evil. Natural evil includes suffering caused by events like earthquakes, tsunamis, cancer, and famine — things that happen regardless of human action. Moral evil refers to suffering caused by human choices: war, genocide, abuse, cruelty. The philosopher J.L. Mackie argued in his 1955 essay “Evil and Omnipotence” that the existence of evil is logically inconsistent with an all-powerful, all-knowing, all-good God. If God is able to prevent evil (omnipotence), knows about evil (omniscience) and wants to prevent it (omnibenevolence), then evil should not exist. Its existence, Mackie argued, means at least one of those divine attributes must be false — or God does not exist.
Natural evil = suffering from nature (earthquakes, disease). Moral evil = suffering from human choices (war, murder). J.L. Mackie argued that the existence of either type is logically inconsistent with a God who is omnipotent (all-powerful), omniscient (all-knowing) and omnibenevolent (all-good).
Christian Responses to the Problem of Evil
Christian theology has developed several responses to the problem of evil. The soul-making theodicy — associated with the philosopher John Hick and drawing on the early Christian thinker Irenaeus — argues that God permits suffering because it is the necessary condition for human moral and spiritual growth. Just as muscles strengthen through resistance, character develops through challenge. A world without suffering would be a world without the opportunity to develop courage, compassion, or perseverance. Irenaeus described humanity as made “in the image of God” but not yet fully in the “likeness of God” — suffering is part of the journey towards that likeness.
The free will defence — developed by Alvin Plantinga — argues that God created humans with genuine freedom to choose between good and evil. Moral evil is the result of people misusing that freedom. A world in which God prevented every act of evil would require removing human free will, and a world of puppets doing only what God programmes them to do would have less moral worth than a world of genuinely free agents. Many Christians draw on Genesis 3 (the Fall) to explain how human sin entered the world through Adam and Eve’s free choice to disobey God.
In Islam, suffering is understood within the framework of qadar (divine decree). Muslims hold that God is entirely just and that all suffering ultimately serves God’s purposes, even when humans cannot understand them. Suffering is seen as a test from God: “We will surely test you with something of fear and hunger and a loss of wealth and lives and fruits” (Qur’an 2:155). Patient endurance (sabr) in the face of suffering is itself a form of worship. Islam also emphasises that natural evil does not originate from a devil equal to God — there is no dualism; God alone is ultimate.
In Jewish tradition, the problem of suffering is powerfully explored in the Book of Job. Job is a righteous man who loses everything — family, health, wealth — not as punishment for sin but as a test. Job’s response is to continue trusting God even when he cannot understand why he suffers. Jewish theology does not offer a single theodicy but encourages wrestling with the question honestly. After the Holocaust, many Jewish thinkers such as Elie Wiesel and Emil Fackenheim engaged deeply with the question of how God could permit such suffering, with varying conclusions about faith and protest.
Arguments Based on Science
Alongside the problem of evil, modern science has provided alternative accounts of the universe’s origin and development that some argue make the existence of a creator God unnecessary. The Big Bang theory, developed through the work of Georges Lemaître, Edwin Hubble and others in the 20th century, describes the universe as originating in an extraordinarily rapid expansion from an extremely dense initial state approximately 13.8 billion years ago. This is supported by multiple independent lines of evidence: the observed expansion of the universe, the cosmic microwave background radiation, and the relative abundance of light elements.
Charles Darwin’s theory of evolution by natural selection, set out in On the Origin of Species (1859), explained how the diversity and complexity of living organisms developed over billions of years through random variation and the survival of the fittest. Atheist scientists and philosophers such as Richard Dawkins argue that evolution removes the need for a designer God: once we understand how complex life arises through natural selection, the Design argument loses its force. The universe, on this view, is explicable entirely in terms of natural causes.
Many students write that “science has proved God does not exist.” This is inaccurate and loses marks. Science describes how the universe operates through natural processes; it cannot, in principle, disprove the existence of a being outside or beyond the universe. What science does is remove the necessity of a God-explanation for specific things — the origin of species, the age of the Earth — by providing natural explanations. Many religious believers, including the Catholic Church (which teaches that evolution and Big Bang cosmology are compatible with belief in God as creator), accept the findings of science while continuing to believe. The debate between science and religion is more nuanced than a simple clash.
Atheist and Humanist Perspectives
For atheists, the combination of the problem of evil and scientific explanation makes belief in God unnecessary and unjustified. The ancient Greek formulation attributed to Epicurus is still quoted: if God is willing to prevent evil but unable, God is not omnipotent; if God is able but unwilling, God is not good; if God is both willing and able, why does evil exist? Bertrand Russell famously stated that there is no sufficient reason to believe in God and that the problem of evil in particular makes the idea of a benevolent creator implausible.
Humanism, as represented in the UK by Humanists UK, holds that human beings can live ethical, meaningful lives through reason, compassion and humanity alone, without the need for religious belief or a divine lawgiver. Humanists do not regard the problem of evil as a dilemma they need to resolve — they simply do not begin with the assumption that an all-powerful, all-good God exists. For humanists, suffering is a natural fact of a universe governed by physical laws, and the appropriate response is human solidarity and action to reduce suffering, not prayer or theodicy.
The free will defence: God gave humans genuine freedom to choose; moral evil is humans misusing that freedom, not God’s fault. Counter-argument: free will does not explain natural evil (earthquakes, disease) — these are not caused by human choice.