I used to get tripped up by this as well. Let me attempt to explain it to you. What does the term "exist" mean? What if you destroyed every chair in the world, does "chair" no longer exist? How is it that I could still use the word "chair" and you would know exactly what I am describing? Could it be that "chair" exists beyond is physical manifestation? It represents a concept/idea/apparatus that has specific meaning? If this were not the case how is is possible to make a chair after all chairs have been destroyed? Now imagine "God" and "Satan" as archetypes that help describe universal truths and the nature of reality with an implied set of values. Those values break down to there being behaviours/actions that you do and there are behaviours/actions that you KNOW you OUGHT to do (or ought not do). Life is suffering and our choices impact our lives and the lives of those around us by contributing to either the reduction or increase of suffering. You probably use different terminology to describe this truth and that is fine, or maybe you have different set of values. Either way, wether you choose to use this terminology or not the concept exists and is actually surprisingly specific. The "God" and "Satan" archetypes contains nuance that simplifies speaking about complex topics that everyone deals with. Once you understand this you will find that using these religious archetypes can be a huge time saver and it actually has more precision than you initially would realize.  For example, "These rights are God given and it is the duty of the government to protect those rights." is a lot easier than trying to describe the complexity of what role government has and why there are certain things that are beyond the reach of government such as controlling thoughts/speech etc. It's easier to just say "God given" and be done with it. When you hear "God" or "Satan" don't tripped up on what is factually correct or not, instead try to understand what is being said by the person using the terminology.