Then the serpent said to the woman,You will not surely die. For God knows that in the day you eat of it your eyes will be opened, and you will be like God, knowing good and evil.
It must have been a hard decision for God to make. I don’t mean to suggest that anything is really hard for God, but the decision had consequences that even God could not have treated lightly. The decision to put the tree of the knowledge of good and evil in the Garden of Eden had consequences for all of history. By putting that tree there, God effectively created a gate out of the Garden of Eden. He gave man a choice about the kind of a world that he would live in. If Paradise became boring for man, he had an alternative.
God (1) told Adam and Eve not to eat of the tree, but (2) left them free to eat it anyway. Much is contained in these two simple facts. But there was more. In order for God to achieve his objective, it was necessary that man be free. But that idea has terrible consequences. If man is not free to do evil, for example, he is not free. If he is not free to hurt other people, he’s not free. If man is not free to suffer, then he’s not free. If the innocent are not free to suffer at the hands of evil men, then they are not free.
Liberty has consequences. Man wants freedom, and at the same time he wants to be free from the consequences of his actions. These two wants simply cannot be reconciled.
Why is evil allowed in God’s good world if God is good? The answer is utterly simple: God is good, man is free. And if you’re not free to do evil, you’re not free at all.