SAM said:
Are there any statistics as to where atheists are most likely to be actually killed for lack of belief?
Quite a few people have been killed in Latin and South America for being "godless communists", especially if they attempted to organize trade unions or write newspaper articles.
But whether "lack of belief" was the offense or not is debatable. It's hard to spot atheists, in communities that threaten them. Very few of the atheistic Catholic priests are visible, for example.
Since the rise of science as a set of organized disciplines, de facto atheism has become much more acceptable to those who wish to enjoy the benefits of reliable description of the natural world. The opportunity cost of killing atheists is pretty high, these days.
The various Inquisitions and so forth in Christian Europe did fade. There are places in the Islamic world where atheism is a dangerous admission, but for some reason few atheists are found there.
The matter is complicated by the practice of declaring one's enemies to be "atheist", in the case of their practicing a different and therefore invalid version of Deity worship - whether the Catholics were killing the Protestants in Europe, or the Inca in Peru, because of their atheism as defined by the Church, is a slippery issue.