Just How Many People Has Religion Killed?
Kirk Durston, National Director, New Scholars Society

A popular urban legend that I've often heard is that religion has killed more people than anything else, so the world would be a lot more peaceful place were it not for religion.
The top three largest examples are thought to be the Crusades of the Middle Ages, the Spanish Inquisition, and the burning of witches. Scholars estimate that the Crusades of
the middle ages cost from 58,000 to 133,000 lives. The most realistic figure for the Spanish Inquisition puts the total killed from AD1480 to AD1808 at up to 31,912.
Finally, records indicate that the number of witches killed may be over 30,000. Some argue that records don't tell everything and suggest that maybe even 100,000 were killed.
These three events, totaling over 264,000 killed, are thought to be the largest atrocities perpetrated by one or another form of Christendom.

According to University of Hawaii political scientist Rudolph J. Rummel, the total number killed in all of human history is estimated to be about 284,638,000. Of that number, 151,491,000 were killed during the past 100 years. The single largest killer in all of human history is, by far, atheistic
Communism with a total of 110,000,000 … over 1/3 of all people ever killed! If we add to that number just two other regimes where religion of any sort was strongly discouraged, Nazi Germany and Nationalist China, the number rises to 141,160,000.
Almost 50% of all the killings in human history were committed in the past 100 years by regimes that either actively promoted atheism or strongly discouraged religion.

source: (blue clicky not working at this end)

http://www.hawaii.edu/powerkills/NOTE1.HTM