A nihilist is non de facto an atheist. Besides I know of no atheist personally who is like that yet I know several Christians who have admitted they would rob and murder without their deity.
They were probably just talking, wrongly thinking that it was a good argument for believing in God.
I personally wouldn't rob or murder anybody, with or without faith in God. But I did become a better son to my parents, a better brother, a better friend, a better student, a harder and more responsible worker and a more responsible borrower after I became a Christian.
And I have known of atheists who, just talking, admitted they would probably rob, rape and murder if they did not fear the law of the land and the consequences if they got caught.
Then there are atheists such as Mao Zedong, Joseph Stalin, Pol Pot who killed millions of innocent people just because they were above the law and could get away with it.
You spent some time in S. Korea. You posted that they are very dishonest people and that they robbed you and treated you like trash for two years. You expressed that you had come to hate them and that you wished N. Korea would invade them and that they would all killed each other. Weren't you "just talking" when you said that? I believe you were.
If you were serious about that, wouldn't you kill them all yourself if you had the power at your finger tips? No? You'd rather have the N. Koreans do your dirty work for you?