God Doesn't Believe in Atheists
And neither should we!
There are only two types of people in this world: Those that profess Jesus Christ as Lord and Savior (Romans 10:9), and those who ultimately reject Him.
Scripture makes it clear in several places that when we stand before our Creator we will have no viable excuse for rejecting God. Romans 1:18-20 says, "For the wrath of God is revealed from heaven against all ungodliness and unrighteousness of men, who hold the truth in unrighteousness; Because that which may be known of God is manifest in them; for God hath shewed it unto them. For the invisible things of him from the creation of the world are clearly seen, being understood by the things that are made, even his eternal power and Godhead; so that they are without excuse."
The key points in those verses tell us God's wrath has been revealed against ALL ungodliness and unrighteousness of men (yes, God is love but His wrath is something to acknowledge also), and that the truth of God is manifest in them. Knowledge of God is manifest in who? MAN. All humankind.
Moving on, the invisible things of God (His divine attributes) are clearly seen through His creation. Or, as Adam Clarke puts it, "His invisible perfections are manifested by his visible works." Even God's eternal power is plainly apparent which leaves ALL people without any excuse. Even though the gentile world did not have the law and the prophets to guide them, God does not hold them guiltless because of the various ways He has revealed Himself.
Romans 2:14-15 provides more information on this topic: "For when Gentiles who do not have the Law do instinctively the things of the Law, these, not having the Law, are a law to themselves, in that they show the work of the Law written in their hearts, their conscience bearing witness and their thoughts alternately accusing or else defending them." So even without the Old Testament law, ALL people have had the law Divinely imprinted on their hearts to know right from wrong.
In many cases, professing atheists talk more about God that many Christians! Why would that be if they truly didn't believe in a god? They know in their hearts that God is real, but they suppress the truth in unrighteousness. They love their sin too much to submit to Holy God. You'll find that every unbeliever rejects God, not for intellectual reasons, but exclusively for emotional reasons. They are rebellious against Almighty God, and want to do what seems right in their own eyes rather than allow God to rule in their lives.
Check out https://www.godorabsurdity.com/ for another look at this!