Ayn Rand insisted that it was. She viewed Christian charity as weakness and foolishness.
Answer:
There is no canon of needed atheist beliefs. Aside from the fact that, by definition, atheists do not accept the existence of deities there is no further list of how they must behave, relate to others, society, nature or anything. Some atheists may hold opinions in direct opposition to other atheists. This does not stop them from being atheists or even be classed as a subset of atheist.