No, it's about not seeing any convincing evidence for the existence of supernatural beings.
That would make someone an agnostic, not an atheist. Atheists go beyond that to assert a negative, that God does not exist. Since a negative cannot be proven, they have to accept that on faith, just any other religion. Basically they have to believe that 14 billion years ago the entire universe, matter, energy, time and space, and all the physical laws of the universe spontaneously came into being in a nanosecond and completely rule out the possibility of a higher intelligence behind it.
That doesn't make them evil. But I can see how some evil people could gravitate towards a belief that negates any higher morality or consequences for their actions beyond this life.