The No True Atheist argument

Atheist: Atheists do not condone evil. They do not have people murdered for atheism does not require murder.
 
Christian: But what about the likes of Mao who said they were atheists and who facilitated genocide of innocent people?
 
Atheist: But they were not real atheists at all.
 
So we have a form of the ridiculous and fallacious No True Scotsman argument.

The argument should be:

Atheist: Atheists do not condone evil. They do not have people murdered for atheism does not require murder.
 
Christian: But what about the likes of Mao who said they were atheists and who facilitated genocide of innocent people?
 
Atheist: But they were not acting as real atheists at all when they killed. They did not say, "I will kill because I do not believe in God."

There is nothing wrong with that argument.