2+2 = 5 for very large values of 2”, read the phrase on Lawrence Krauss’s T-Shirt as he put his suit aside. The crowd erupted in laughter and puzzlement as he was giving his lecture. You'd be forgiven for scratching your head if you read the phrase. If common sense is respected then 2+2 can never equal 5. Addition only works one way. The phrase on Krauss’s shirt is a logical contradiction. Ironically, Atheist philosophers have long claimed that there is a similar logical contradiction in the following two sentences: “God exists. There is evil in the world.” According to them, there is no rational way to believe both things at the same time. This supposed 'Problem' is what we call the Logical Problem of Evil.
The Atheist says Evil and God cannot logically coexist together in the same way that a married man can’t also be a bachelor. According to the Atheist, even one instance of Evil in the world is logical proof that God does not and cannot exist. Why? Because there is no morally sufficient reason, none whatsoever, for a God powerful enough to create the Universe to allow evil in the world.
Unsurprisingly, this is a weak argument against the existence of God. All the Theist has to do is come up with one sufficient reason for allowing evil and the logical problem vanishes. If someone claims “It is illogical that a human can fly”, all that is required to refute him is to give him a plausible way a human can fly in the air. Similarly with the logical problem of evil, you just have to give a plausible reason. The reasoning doesn’t even have to be true. You can say like the Christian that evil exists in the world because it has been inherited, like a virus, from our ancestors who misused their will. You can say that having freewill is a morally sufficient excuse for allowing evil. Any number of sufficient reasons could be given for God allowing evil. So, this argument fails miserably, and it is the only argument that directly tries to prove that God cannot logically exist.
No other (respectable) atheist argument tries to prove that God’s existence is impossible. Rather, they try to tarnish the image of God, or decrease the likelihood that He exists. If you accepted all of their arguments, you could claim that the god that exists is a distant one not concerned about human life, or you could claim that it is a force of nature, or that it is an evil god, or that it’s more likely than not that God exists. But you could never claim that a God does not exist and you could never claim that the belief in God is rationally illogical or impossible. Anyone who does so is simply ignorant.
This simple refutation of the logical problem of evil shows us something important about belief. The believer in God has many proofs confirming his belief in the existence of a God. But the disbeliever in God only has criticisms of the believer’s proofs. He has scant proofs of his own - proofs that crumble easily under careful thought.
Allah instructs the Prophet peace be upon him to say to the non-believers:
قُلْ هَاتُوا بُرْهَانَكُم إنْ كُنْتُم صَادِقِين
“Bring your clear proof, if you are truthful.”
The proofs of God are both clear and come naturally to the human intellect. If some are so lost in their own intellects that they end up denying them, the man of sound reason should not doubt himself. No man with half a brain will believe 2+2 = 5 just