By any practical measure, there's no difference between a god or gods and the creator(s) of a simulation. In either case, that creator is the omnipotent, omniscient builder of our reality and existence. So I would argue that one cannot be an atheist and believe in simulation theory, and that evidence for simulation theory in fact points to the existence of a higher power creator.
Simulation theory is nothing more than a bunch of atheists inventing God, but with extra steps.
By any practical measure, there's no difference between a god or gods and the creator(s) of a simulation. In either case, that creator is the omnipotent, omniscient builder of our reality and existence. So I would argue that one cannot be an atheist and believe in simulation theory, and that evidence for simulation theory in fact points to the existence of a higher power creator.