My round 1 argument is the general answer I tend to give. If you want to get into semantics. I'm overjoyed to do so.
In this case of proving the identity of something, absence of evidence is evidence of absence. In my humble opinion.
Would you agree that things that don't exist are absent?
Would you agree that things that don't exist can't have evidence?
Would you agree that absence of evidence is a good reason to be suspicious when everything known to exist has evidence?
Let's do roots.
The-ism
The = God , Ism = belief.
Claims a belief in a god.
A - the - ism
A = without, The = God , Ism = belief.
Claims the NOT have a god belief. Does not claim to have a NO God belief.
Anti-The-ism
Anti = Against/Reject/Deny , The = god , Ism = Belief.
Claims a NO God belief.
square is a rectangle, but rectangle is not square.
Thumb is finger, finger is not thumb
Antitheist is atheist, atheist is not antitheist.
sorry but you're wrong here.