the problem of Christians suffering. Indicating a God who does not care, even about His own people.
the problem of human ecocide - very short-lived human species when compared with very long-lived dinosaurs.
the problem of human intolerance of each other and their inability to live in peace one with the other.
the problem of the vast majority of the best Christians - the Bible believing, born again ones - being quite content with having employment in the arms industry, the armed forces and voting for the war parties. Coercion, force and aggression is acceptable for the most virtuous, sanctified and holy of people.
the problem of abortion and voluntary euthanasia being more evil than killing the born in time of war.
the problem of human stupidity - especially over foreign, military, transport, economic and energy policy - not much left after than list. But, actually, we humans are homo sapiens - "wise man" - so we can't be that stupid!
the problem of the infinite, immensities of space, of nothingness yet the existence of earth created by the human construct of ‘God’.
the problem of how God came about, if He was not thought up by humans.