What is the definition of God?

So I've been reading through R&S section and after seeing numerous quarrels, statements, etc., I've got really confused at some point. The whole bunch looks to me like a group of impatient people who can't agree how they will call something. Example: "God created people" VS "Evolution created people". Lots of words are said about this but I really wonder why people care so much about what set of letters will describe the process/phenomena that resulted in us being created? After some further thinking, I realized that I lack the actual definition of God. So the question is: what is God, how do you define God? What set of properties or whatever I need to look for to clearly tell - this is God and this is not God?