The kind of faith an atheist has
The problem with this attitude, and that of the atheist quoted in Rabbi Yuter's blog, is that he doesn't understand that atheism, or each of its various varieties, is a religion like any other, with its good followers and its bad followers. Surely more people were killed in the 20th century by fanatical followers of Communism, a variety of atheism, than by followers of any other religion, mostly in Stalin's Russia. And yet, at almost the same time, in the early 1940s, in nearby Poland, the Communists were almost the only decent people, allowing Jews to join their partisans fighting the Nazis, when the Polish nationalist (Catholic) resistance was not allowing Jews to join them, and was even killing Jews.
Atheist religions, like theist religions, are capable of inspiring the best and the worst in people. And it doesn't help to say that you are using a scientific, empirical method to determine what is moral behavior. That is precisely the claim that Marx made for Communism. It is the very "ends justify the means" philosophy of Communism, which would surely claim that it is seeking the greatest happiness for the greatest number (eventually, in a future utopia), that made possible its worst behavior.