According to atheistic philosophy the fact that there is evil in the world is proof that God does not exist. At best God is some strange entity that is either perverse or weak. They base this on the following syllogism: (1) God is all knowing (omniscient) (2) God is all powerful (Omnipotent) God is all loving (Omnibenevolent) (3) Yet evil exists
This according to atheists is faulty reasoning. Either God is not all powerful, i.e. he can't do anything about evil. He himself is in some sort of dualistic war with evil. Or he is not all loving and takes some sort of sick pleasure in evil.
I would agree that this syllogism is faulty. That is because something is lacking. How can we as Christians account for the existence of evil?
A proposed solution to the problem of evil is known as a theodicy. Here is a Christian theodicy.
God has a morally sufficient reason for allowing what evil that exists to exist. We may not know what that reason is but we trust that evil is at his disposal for good. "All things work together for good to those that are called." "I make peace and create evil." Remember Job. Remember Joseph "you meant it for evil but God meant it for good."
God is not the author of evil. Satan and man have done their part in this respect.
It is only in a Christian worldview that we can account for the existence of evil. In fact those that object to something as being evil must have some sort of standard of good by which to contrast the evil with. They do not have such a standard! Something is wrong because they say so. This is a far cry from God saying so. Atheistic systems of ethics, teleological, deontological, utilitarian, virtue ethics, etc. and their versions of any sort of theodicy accounting for evil are mutable and absurd.