A decade ago, Gary Deddo taught our Systematic Theology class what he called "The First Theological Question" ... "Who is God?"
This questions shows up over and over again in Scripture. Moses movingly asks the question as he contemplates his calling and Pharaoh asks it sardonically before his kingdom crumbles. David's answer to the question launches him at Goliath. And, most significantly, Jesus asks his disciples to answer the question for themselves.
Who is God?
Answer that question wrongly and a lot of things will fly off the rails.
Many of the people who don't believe in God would answer the "Who is God?" Question in ways that would be unrecognizable to those of us who love Jesus. They see him as an absentee landlord or an angry warmonger. When they tell us about the God they don't believe in, we say "We don't believe in that God either!"
How do you answer the "Who is God?" Question? Where would you even start?