So about God. if you start with the idea that God is omnipotent. then the matter is that God can decide do or not do something. like when you turn of the light. so when God decides not to whow his light in punishment to the world, there is darknes in the world. thats why Jesus said that christians are the light of God.
its not a flawed concept, the problem is that atheist arent interested in poeple to know what it means,so you need to go find sources that will teach you what you need to know. other way is like trying to ask Stalin if freedom of speach is a flawed concept.