Christians and Muslims love making fun of pagans.
In paganism, God can be considered evil.
However, Christianity and Islam both claim maximally good God.
At same time, they claim evil exists in the world.
Problem with these two claims is that if evil exists in the world, it is caused by their God.
For start, their God, maximally good God, stands and watches while somewhere in the world, children drown or starve. This happens every day in this world.
God who is maximally good seems to be completely okay with not stopping any horrible thing.
But is God merely "not acting"?
No, God also caused all evil in the world.
All evil in the world is caused by God's design. It is God who designed animals to devour each other. It is God who designed world where people can not only hurt each other, but find countless ways to do it.
Also, God gave many people evil urges, making them gain pleasure from doing evil.
It's impossible to divorce God from evil.
Not even free will can do it, because it is still God choosing to create evil out of someone's free will. Why should free will of one man be able to cause harm to another? Because God created the world in such way that these things are guaranteed to happen.
God cannot be good. It's not logically possible. This is mainly because God also chose to create evil people, and is as result indirectly responsible for their evil.
God isn't merely inactive. He is enabling evil at the very least.
Evil =\= good
Evil = causing bad things, enabling bad things, (all which God does)
God = evil
God =\= good