I think that God lets evil exist so we can truly see him. If everything was pure and holy we wouldn’t see God’s glory to the fullest. But if there is evil we can trust in God and see his true glory against the evil of saint. I also think that he lets evil exist because he can show his true glory through another person. For instance in the Bible there is a man who had been taken over by evil spirits and Jesus cast them out into pigs and the pigs ran into a lake and drown themselves. That passage just really shows that God can do anything and really cares for each and every one of you. You might not be taken over by evil spirits but you still might have evil thoughts of killing someone for instance and God can really be there for you and save you.
Good also lets evil exist because in hard times it lets us see his true love. Many people grow stronger in their faith after a hard time in their life and they always end up looking to God for love and he gives them love. After someone dies that you were close or a huge natural disaster kills someone you know it helps you to get stronger in your faith. It also lets God show you his true love for you and that you are worthy of is love even though you went through a hard time. It’s in the horrific deaths, natural disasters, crazy killers and other evil in this world that we really urn for God’s love and forgiveness to get on with our lives.
Lastly I think God lets us have freedom of choice so that’s why evil exists. It wouldn’t have been as glorifying for God if all day long we just praised him non-stop than if we had freedom of choice. When times get bad we could turn to God for the answer and he would save us. Evil and God’s love is like God and the world. God goes on forever and ever but the world had a starting point and will have an ending point just like God’s eternal love and the short time of evil. Plus most of the evil and suffering has been bad choices by men and temptation by the devil.
I conclude that God doesn’t like evil but he lets it exist so we can learn from it and to grow deeper in our walk with God. Darkness doesn’t really exist it’s just the absence of light. So evil doesn’t really exist it’s just the absence of God’s love. So that is why evil exists so that God can show us his true self and that cares about each and every person.