Dan. You did start the body-count game.
The worst blood lettings of the 20th century.
Rank Death Toll Event Dates
1 55,000,000 Second World War (Some overlap w/Stalin. Includes Sino-Japanese War and Holocaust. Doesn't incl. post-war German expulsions) 1937/39-1945
2 40,000,000 China: Mao Zedong's regime. (incl. famine) 1949-76
3 20,000,000 USSR: Stalin's regime (incl. WW2-era atrocities) 1924-53
4 15,000,000 First World War (incl. Armenian massacres) 1914-18
5 8,800,000 Russian Civil War 1918-21
6 4,000,000 China: Warlord & Nationalist Era 1917-37
7 3,000,000 Congo Free State [n.1] (1900)-08
All SECULAR
For a Grand Total of 145,000,000 dead bodies chalked up to the non-religious.
And I could go on.
This alone, in just under 80 years dwarfs anything religion has achieved, and I could continue to add to it.
Blacknad.
