They cannot disprove God but disbelieve despite that! This is important. They assume that God can be proved (or disproved) when the Bible doesn't attempt to do it but to make Him known. The Bible assumes God from verse one. The Bible says that God’s existence has enough proof in creation to point to faith and that no one has an excuse. (cf. Romans 1:18–21; Psalm 19:1). God is spirit. The question of God is metaphysical and cannot be proved by physical evidence. God’s existence doesn’t fit scientific parameters; He is not subject to laboratory conditions.
Many people believe in things that cannot be proved. What they are trying to do is equate God’s existence to scientific scrutiny. But there is scientific evidence but no proof. The laws of evidence are different for law, history, science, and philosophy. God doesn't wish to be proved but to accept by faith. He will not force faith. Faith is what pleases Him, not human wisdom (“For the world by wisdom knew not God.”—1 Cor. 1:21). It is logical that not believing or denying some premise doesn't make it untrue any more than believing it makes it true.
There can be no default position. Not being able to prove God doesn't mean that the antithesis is true, there is no God. Today many people will not believe anything that cannot be proved scientifically and use science for non-scientific endeavors or issues, harnessing science where it doesn’t apply—called “scientism.” You don’t have to know all the answers to believe in God. And faith doesn't mean you do, atheists don’t know all the answers either. The principle stands: “Lack of evidence is not evidence of lack.”
Addendum:
Science rules out God from the get-go and disbelieves in the supernatural as a possible answer in their live pool of options. They are naturalists believing everything has a natural explanation. But anyone who thinks Christianity and science contradict understands neither—there can be no final conflict in God’s universe. Augustine wisely said, “All truth is God’s truth.” The Bible has proved time and again to be ahead of science in its truths. The Bible has proved time and again to be ahead of science in its truths with dozens of scientific facts stated before discovered by science with no scientific absurdities.
Soli Deo Gloria!