Explain the problem of suffering.

The problem of suffering is the apparent discrepancy between the existence of God on the one hand, and the occurence of suffering in the world on the other. The problem results from the fact that traditional theism – in other words, the traditional beliefs of the three Abrahamic religions – define God as omnipotent (all-powerful) and omnibenevolent (all-loving). If God is omnibenevolent, he has the desire to prevent suffering; if he is omnipotent, he has the power to do so. Surely then, it may be argued, if God existed, and he were both omnibenevolent and omnipotent, he would not allow so much suffering?
The problem can be divided into the logical problem of suffering and the evidential problem of suffering. The logical problem of suffering is the apparent impossibility of God and evil existing simultaneously. J.L. Mackie formulates the logical problem as an "inconsistent triad" of three propositions: (a) "God is omnipotent"; (b) "God is omnibenevolent"; and (c) "Suffering occurs." Mackie argues that, if suffering occurs, God could be either omnipotent or omnibenevolent, but not both. In other words, he could have the power, but lack the desire, to prevent suffering, or he could have the desire, but lack the power, to prevent suffering. But if God has both the power and the desire to prevent suffering, it simply follows logically that he will not allow suffering to exist. Hence, it is simply impossible for suffering to exist, and for an omnipotent and omniscient God to exist at the same time. 
The evidential problem of suffering is the apparent improbability of God existing while suffering exists. People who use the evidential problem of suffering to argue against God's existence tend to believe that the existence of suffering does not make it impossible that God exists: after all, God may have a very good reason for allowing suffering that we do not understand. However, they argue, when one looks at the sheer extent of suffering in the world, it becomes very improbable that God would have any good reason for allowing it to occur. William Rowe uses the example of the fawn who slowly burns to death in a forest fire. He argues that, although it is possible that an omnipotent and omnibenevolent God has some very good reason for allowing the fawn to suffer so terribly, it is very unlikely. Hence, he argues, the suffering of the fawn provides very strong evidence against God's existence.