One thing that we humans can't understand is the HOLINESS of God. Humans are so far behind God in terms of holiness that there is essentially no difference in the level of sinfulness of someone like Hitler, and someone who is a "good person". If Hitler is scored 1,000,000 on sinfulness (evil), and the "good person" is scored 10, they are both INFINITELY lower than God, because God is infinitely Holy. Humans trying to understand God is like an amoeba trying to understand humans.
One thing that we humans can't understand is the HOLINESS of God. Humans are so far behind God in terms of holiness that there is essentially no difference in the level of sinfulness of someone like Hitler, and someone who is a "good person". If Hitler is scored 1,000,000 on sinfulness (evil), and the "good person" is scored 10, they are both INFINITELY lower than God, because God is infinitely Holy. Humans trying to understand God is like an amoeba trying to understand humans.