Concerning atheism, I think the word "atheism" is a very confused (if not overused) term. Indeed, by reading some of the replies in this thread, I felt that some posters actually have confusions regarding usage of the word "atheism". (I am not an exception of this to be honest.)
Although I am not sure about the etymology of the term, I think that, in its strict sense, atheism denotes the disbelief in God or gods. In this sense, actually a Christian can be an atheist because Christians do not believe gods like ancient Egyptian gods, Horus to cite an example. In other words, we can say, Christians are atheists with respect to ancient Egyptian gods. Actually, under this interpretation of the term atheism, Jains and Buddhists are atheists too.
However, throughout the philosophical discourse, it seems that the usage of the term atheism has expanded to denotes many disbelieves. In this expanded sense, a Buddhist person can not be an atheist because according to this extended meaning of "atheism" one should reject reincarnation in order to be an atheist.
I don't prefer to identify me as an atheist because of this confusion when it comes to the usage of the word "atheism". I, instead, identify myself as a humanist.