Atheism does not claim a particular god (or group of gods) does not exist, atheism claims that the Universe requires no supernatural deity in order to exist and can be explained by science alone.
Sorry, I assumed you were using the definition everyone else uses. In the future, it would help if you gave your own definition for terms if you've redefined them to suit your personal tastes.
Judgement of a soul (which meets criteria as supernatural entity on it's own) would be done by what exactly, if not a supernatural being?
Some people believe that they judge themselves during a life review.
Moving said soul into another living creature would be done by what exactly, if not a supernatural being?
I don't need a mechanic to get in my car, or a tailor to get dressed in the morning. Why should a supernatural being be necessary for a disembodied soul to possess a vessel?
Belief in what is convenient is satanism "do what thou wilt" and not atheism. And yes segments of atheism have been taken over by satanic beliefs, and it's been easy to do since people believe in appeals to authority.