A concept that is used, when there is a need to show evidence to the
point of showing that a fact or incident is definitively true or has
happened, who does it? In most cases nowadays, it usually lies within
the person claiming such things that has to do such tasks for it to
become logical.
This is probably the best reason for atheism, so atheists argue that since there is no
empirical evidence for a god, the default position should be non-belief,
just like many myths or childhood hoaxes like the “tooth fairy” (can’t
prove something that is not seen as science relies on observations). It
should be treated with at least equal questioning as other unproven
claims, or perhaps with even more due to the Probabilistic non-God
argument! People even argue that "atheism" should not need to exist as a word, as
words like ascientist or alawyer don't exist. Historically in legal
systems, it was the other way around, which led to many unnecessary
arrests, but it’s corrected in the modern age.