If God is the Creator of all things, where did evil come from?

When you face the source of light like a lamp post you see bright light emanating from it. When you face away from the source of light, what you see is shadow. Now shadow doesn't have an existence of its own. There is shadow because there is light or can you say there is shadow because there is no light there ? If there is light or God everywhere, where did shadow or darkness( evil) come from? Do you see it is just a different way of perceiving things? Milk is good for health. But one cannot have 10 gallons of milk at a time just because it is good, then it will turn bad or evil. Milk was good but the same thing is evil now? A murderer holds a knife and also a doctor holds a knife, but with a completely different intention of saving the patient from the wound. See ? Good/ bad, light/darkness is all based on how we see, based on our intent and utility of things. Good/deep question and the above answer needs more contemplation to actually sink in. Now contemplate on what actually did God create….