It's the impossible triangle. Draw a triangle, and put all seeing at one corner, all loving at another, and all powerful at the last. God claims to have all these charactaristics, but in the end you have to cover one of them up to explain evil in the world.
He cannot be all loving, and all powerful, and all seeing, but allow evil.
He could be all loving, and all powerful, but not see the evil.
He could be all loving and all seeing but not powerful enough to stop the evil.
He could be all powerful and all seeing but not loving enough to stop the evil.
Anyone one of these statements defeats Christianity.