Many terrible things have been done in the name of religion. However, it is inaccurate to say that religion has caused more death than any other cause in history. In fact, the opposite is likely true. Totalitarian regimes who were avowedly and militaristically atheist are responsible for the single deadliest century in human history. Depending on which methodology you adhere to, Stalin was responsible for 20 million - 60 million deaths, Mao was responsible for over 70 million deaths, Pol Pot was a mere piker with only 3 million deaths. I could continue the tabulation of the seemingly endless mass killing propagated by atheistic/secular regimes. It totals bout 250,000,000 in the 20th century alone. This total is a huge multiple of the total of "religiously" motivated killings for the previous 2,000 years.
