Why does God allow evil and suffering? In the philosophy of religion, this paradox is known as the Problem of Evil, often regarded as the “death-blow” to the Judeo-Christian-Islamic deity. 

Russell explains:

“The world, we are told, was created by a God who is both omnibenevolent (all-loving) and omnipotent (all-powerful). Before He created the world He foresaw all the pain and misery that it would contain; He is therefore responsible for all of it. It is useless to argue that the pain in the world is due to sin. In the first place, this is not true; it is not sin that causes rivers to overflow their banks or volcanoes to erupt. But even if it were true, it would make no difference. 

If I were going to beget a child knowing that the child was going to be a homicidal maniac, I should be responsible for his crimes. If God knew in advance the sins of which man would be guilty, He was clearly responsible for all the consequences of those sins when He decided to create man. The usual Christian argument is that the suffering in the world is a purification for sin and is therefore a good thing. 

This argument is, of course, only a rationalization of sadism; but in any case it is a very poor argument. I would invite any Christian to accompany me to the children’s ward of a hospital, to watch the suffering that is there being endured, and then to persist in the assertion that those children are so morally abandoned as to deserve what they are suffering. In order to bring himself to say this, a man must destroy in himself all feelings of mercy and compassion. He must, in short, make himself as cruel as the God in whom he believes. No man who believes that all is for the best in this suffering world can keep his ethical values unimpaired, since he is always having to find excuses for pain and misery.”

— Bertrand Russell, Has Religion Made Useful Contributions to Civilization? (1930)

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Background: Problem of Evil

In the philosophy of religion the Problem of evil is the question of how to reconcile the existence of evil with that of a deity who is, in either absolute or relative terms, omnipotent (all-powerful), omniscient (all-knowing), and omnibenevolent (all-loving). The existence of evil seems to be incompatible with such a God. The Problem of evil is generally formulated in two forms: the Logical problem of evil and the Evidential problem of evil. The logical form of the argument attempts to illustrates the logical impossibility in the coexistence of God and evil, while the evidential form attempts to illustrate that given the evil in the world, it is improbable that there is an omnipotent, omniscient, and wholly good God. It is then generally concluded that a deity with these attributes does not exist. 

Logical problem of evil presented: 

• P1. If an omnipotent, omnibenevolent and omniscient god exists, then evil does not.

• P2. There is evil in the world.

• C1. Therefore, an omnipotent, omnibenevolent and omniscient god DOES NOT EXIST.

Evidential problem of evil presented:

• P1. There exist instances of intense suffering which an omnipotent, omniscient being could have prevented without thereby losing some greater good or permitting some evil equally bad or worse.

• P2. An omniscient, wholly good being would prevent the occurrence of any intense suffering it could, unless it could not do so without thereby losing some greater good or permitting some evil equally bad or worse.

• C3. (Therefore) There DOES NOT EXIST an omnipotent, omniscient, wholly good god.

A third from of the Problem of evil, The Experiential problem of evil, is the difficulty in believing in a concept of a loving God when confronted by evil and suffering in the real world, such as from epidemics, wars, murder, natural disasters where innocent people become victims.

The problem of evil has been extended to non-human life forms, to include animal suffering from natural evils, such as predation and disease, and human cruelty against them.