I think this question comes with too many assumptions. And too black and white. But that's twitter I guess. Whether we like it to hear it or not, people are usually a mix of the two. Not everyone is all good or bad. Fully Atheist or fully Christians. Morals are murky. Some Atheist are more Christian than Christians. And some Christians without realizing it are more Atheist than they would like to admit to. If someone is a true Christian they couldn't be bad as the requirement to being Christian is to live a life worthy of Christ. But we are all only flawed humans and make mistakes. It's a matter of when, not if. On the other side what is "good" to an Atheist is more of a subjective manner than an objective one. Morals are more relative to the societal norms around the person in that particular time. Often times people don't realize that by denying one god they simply will choose another that fits into the top of their moral compass. In this way you can find the the same issues in people of Christianity, also in Atheism or for a another phrasing, Secular tribal behavior. For example, one may deny a religious god. But then adopt an obsession with politics. Which in turn makes their political party that they are align with become their god. Or for others its simply money, or hedonism. Lastly it is difficult to be fully correct in judging objectively without knowing all the details of a deed and the motives behind it. Which is something that is an exclusive aspect to the being of God. This causes both Atheists and Christians to wrestle with what is good or not. And some getting it right. And some wrong. Thanks for reading.