Evil is understood to encompass both moral evil (caused by free human actions) and natural evil (caused by natural phenomena such as disease, earthquakes, and floods). Problem of evil affirms the following three propositions: God is almighty, God is perfectly good, and evil exists. The problem of evil is the question of how to reconcile the existence of evil and suffering with an omnipotent, benevolent, and omniscient God.
An important statement of the problem of evil, attributed to Epicurus is that, “Is God willing to prevent evil, but not able? Then is he impotent? Is he able, but not willing? Then is he malevolent? Is he both able and willing? Whence then is evil?” This argument is being frequently used by atheism for negating the existence of God. If God exists, then he is omnipotent and perfectly good; a perfectly good being would eliminate evil as far as it could; there is no limit to what an omnipotent being can do; therefore, if God exists, there would be no evil in the world; there is evil in the world; therefore, God does not exist.
St Augustine confronted this debate between presence of God and the presence of evil. After a long intellectual process he arrives at a notion of evil which allows him to affirm that God is not the cause of evil. For Augustine evil is a negative reality. It cannot exist by itself. It is an absence good. Evil exist in a substance, which is good, and it is the privation of a perfection which the substance should have, but does not have. Therefore, evil is not a positive reality, but a privation of reality.
What is the cause of evil? St Augustine’s answer is creature. Evil presents itself in two forms: a. Suffering and b. Guilt. The cause of suffering is guilt. Therefore, the problem of evil is reduced into the problem of guilt. What is guilt? Guilt is the submission of the human reason to passion, in disobeying divine law, and in distancing oneself from the supreme good. When man distances himself from the immutable good to instead turn to a lower and particular good, he sins. This is evil.
This distancing from the supreme good from the part of human being is out of freedom. Therefore, we can say that evil is the consequence of human freedom, which is good.