Hello Frako,
The question how can a omnipotent and benevolent God allow evil is one of the oldest and most discussed philosophical contradictions in Christianity.
You could spend entire semesters in seminary
school on this one subject alone.
The first question on must answer is do you believe in the literal interpretation of the bible. I happen to know you are a atheist so in that context I will say the God of the bible is a collection of stories by bronze age jewish priest who for various reasons wrote these stories. The stories where packaged up and adopted by the Catholic church who maintained power until the Protestant reformation.
In order to fully understand the contradiction one must understand ancient levitical, mesoritic laws and jewish culture. Many of the fire and brim stone stories of the OT God of Israel began from ancient Babylonian myths ie: creation stories. The gods of Babylon had one in particular that was adopted named IL. A region known as edom had a god named Yahweh that was eventually adopted by the people of Israel. This God was all powerful and had no trouble conducting himself in the manner we know as the vengeful god of old. People back then understood that sin and not keeping the laws of Yaweh would bring the full wrath of this God upon them. The Musilim god Allah being one who maintains this bad temper and will put you to the fire if you do not abide the koran. It was the Christians who eventually soften the demeanor of God into one who is less vengeful, and culminating into man himself. A forgiving loving good God.
Whole point being all this literature was collected over centuries and spliced together. Reconciling these text are what makes for christian theology and redacting conflicting passages. So to answer your question is God good or bad I would answer that for you it is a moot point since you do not believe such a entity exist.
However, many Christians reconcile the contradiction by stating that God is not the storm, he is not the damage caused, He is the quiet after the storm, he is the peace that comes from the surviving the storm, the good will and hope in people, that is born from such tragedy.
All the above is a matter of personal opinion and has no basis in fact, so take it with a grain of salt.
"You were not there for the beginning. You will not be there for the end. Your knowledge of what is going on can only be superficial and relative" William S. Burroughs