Let’s turn that around. Why do theists accept the word of their elders about things that no one ever saw or heard, things that just got passed down for thousands of generations? What makes them think a god exists that they can’t see or hear or touch, a god who never does anything?
Maybe you say, “But the Bible says so.” QUESTION: How do you decide to trust the Bible, when no one knows for sure who wrote it, but not scientific journals with names and dates and methods all spelled out for how scientists arrived at their conclusions? If you don’t believe the scientist, you can always repeat the experiment (providing you have the proper training and equipment) to prove him right or wrong. It’s expected.
But for me to say “God exists” when there is no reason to believe so for lack of evidence is for me to lie, bear false witness. Bearing false witness breaks one of the Ten Commandments. Is that what you want me to do? The Bible says all liars go to hell. I feel better if I don’t lie, but speak honestly. It just feels better, it leaves my mind clearer to deal with life head on. But it does leave me vulnerable to accusations of “atheist” by people who think atheists are evil people.
Bottom line: Your question is twisted.