The bible is filled with atheist. God always treated them as simply people who had chosen death, but welcomed them any time they chose life. God teaches us, and they can come to us to learn. God sometimes uses them to work out His plans, but God simply leaves them alone otherwise except to be sure we welcome them if they want to come to Him.
I sometimes listen to them when they discover a way that God operates our world. They often say how smart they are when they tell us, as if they didn't discover a way of God, but they take credit for it. I check scripture with their discovery and sometimes it explains scripture. I'm sure you have all read about when the world discovered that when God said the four corners of the world it didn't mean it was flat.
I don't think God wants us to debate with them. They are spiritually blind, that is the beginning and end of their thinking. They are dead. God can make them live, but it wouldn't be our arguments that did it, but their opening themselves to God and God entering in.