What do you think is the root of all evil?

The existence of free will. Evil is simply what comes about when humans go against God’s wishes. If humans didn’t have free will, they would have followed God’s plan perfectly and they would have committed no evil. Evil is like darkness. God is light and the further you stray away from Him the more you end up in darkness. So God is not directly responsible for evil because evil is what happens when we turn away from Him. But He is responsible for creating a system in which evil can take place.

You may be interested in my essay: Why God Allows Evil to Exist, and Why Bad Things Happen to Good People