A common argument against organized religion is the claim that religion has been responsible for more wars, and hence millions of lost lives throughout history. This is a fallacy – one that is easy to refute by simply studying the history of past wars and culling out contributing causes for the conflict. What you will find is that there is rarely a single cause for war and contrary to atheist claims, religion seldom serves as the primary motivator for war (albeit several wars were led by leaders who thought themselves to be “gods”). In fact, most wars are started for one of four reasons – territorial gains, political differences, economic advantage, or a rebellion against a repressive government. Even wars widely thought of as religious conflicts (e.g. The 30-Year War, The Crusades), when viewed from a rational perspective, were really attempts to gain or regain territory or autonomy.

Religion not as a cause, but as a motivator

Although rarely the cause for wars, it’s important to recognize that leaders may use religion and other common cultural adhesives to unite the country during the conflict, mobilize participants, and to justify their actions using rhetoric. Similarly, when opponents are followers of a different religion, military leaders may use this as an incentive for battle-weary soldiers.  Regardless, this does not imply religion was the *cause* of the war as many religious detractors seek to claim.

Top 20 wars (in terms of loss of life)

Below are the top 20 wars (conflicts) with regards to loss of life (on average). Listed is the name of the war, the estimated number of dead, the years the war took place in, the duration of the war, and the general location. This list also includes general anthropogenic (human-made) disasters.


World War II 40-85 million 1939-1945 6 years Worldwide
Three Kingdoms 36-40 million 184-280 96 years China
Mongol conquests 30-40 million 1206-1368 163 years Eurasia
Qing dynasty conquest of Ming dynasty 25 million 1616-1662 47 years China
Taiping Rebellion 20-100 million 1851-1864 14 years China
World War I 15-65 million 1914-1918 4 years Worldwide
Conquests of Timur-e-Lang 15-20 million 1369-1405 37 years Timurid
An Lushan Rebellion 13-36 million 755-763 9 years Medieval warfare
Chinese Civil War 8 million 1927-1949 22 years China
Russian Civil War 5-9 million 1917-1921 5 years Russia
Napoleonic Wars 4-7 million 1803-1815 13 years Europe
30-year War 3-11 million 1618-1648 31 years Roman Empire
Yellow Turban Rebellion 3-7 million 184-205 22 years China
Second Congo War 3-5 million 1998-2003 6 years Congo
Holodomor 3-8 million 1932-1933 1 year Ukraine
Hundred Year’s War 2-3 million 1337-1453 107 years Europe
European colonization of America 2-100 million 1492-1900 408 years Americas
French Wars of Religion 2-4 million 1562-1598 37 years France
Shaka’s conquests 1-2 million 1816-1828 13 years Southern Africa
War in Afghanistan 1-2 million 1979-2000 22 years Afghanistan



Wars and their causes

Below I examine the cause of each of the Top 20 wars beginning with the deadliest conflict of all, World War II.

World War II

Primary cause: Territorial expansion

Considered to be the most devastating war in human history, World War II took the lives of 40-80 million people across the globe. As with most wars, several events converged at an inopportune moment in time and served to trigger the world’s greatest war. Italian fascism promoted by Benito Mussolini lead to a desire to restore and expand Italian territory in the 1920’s. A similar scenario played out in Asia where Japanese militarism and invasions of China escalated in the 1930’s. All came to a head in 1933 with the Nazi Party’s takeover of Germany. Territorial skirmishes then spun into a full-blown war that drew nearly all of the world’s major economic powers into the conflict.

Three Kingdoms

Primary cause: Infighting between warlords, territorial expansion

The Three Kingdoms period was one of the bloodiest in Chinese history. Beginning with the Yellow Turban Rebellion in 184 AD, the Three Kingdoms period was marked by chaotic infighting between warlords and battles for territory. Fighting between warlords continued until 280 AD by which time between 36 and 40 million citizens had lost their lives. Buddhism flourished after the period of conflict but was not a contributing cause of the conflict.

Mongol conquests

Primary cause: Territorial expansion

Led by Genghis Khan, the Mongols expanded their empire through a series of bloody conquests. Any towns that resisted the Mongol incursions were utterly destroyed. Areas such as Iran, Iraq, Syria, and parts of Turkey were assimilated into the Mongol empire. Far from a religious war, the Mongols were very tolerant of other religions and Genghis decreed religious freedom in every area conquered.

Qing dynasty conquest of Ming dynasty

Primary cause: Rebellion against repressive government

The Manchu conquest of China, also known as the Ming-Qing transition, began with a list of seven grievances against the Ming dynasty’s domination. The grievances related to territorial disagreements and issues of repression. Not a single grievance was related to religion. By the end of the 47-year conflict, 25 million people lost their lives.

Taiping Rebellion

Primary cause: Rebellion against repressive government

The Taiping Rebellion was a massive civil war in southern China against the ruling Manchu Qing dynasty. The war, led by Hong Xiuquan, included various social reforms including equality for women, banning of polygamy, and the abolition of foot binding. Hong did attempt to replace Chinese folk religion with a bizarre form of Christianity in which he was a deity but organized religion played no role in the rebellion which was nothing more than an uprising against a repressive government.

World War I

Primary cause: Series of diplomatic crisis

The First World War began after the assassination of Archduke Franz Ferdinand of Austria. This set off a diplomatic crisis that triggered the breakup of international alliances. Within three weeks, major powers were at war and the conflict soon spread around the world. By the time the war ended 4 years later, between 15 and 65 million people perished. Religion was not a factor.

Conquests of Timur

Primary cause: Territorial expansion

Tamerlane, was a Turko-Mongol conqueror and the founder of the Timurid dynasty in Central Asia. He envisioned the restoration of the Mongol Empire of Genghis Kahn. Tamerlane referred to himself as a deity or “supernatural personal power” and patronized religious (and educational) institutions during his conquests. Timur was in simple terms, a power monger who sought control of territory through various wars and expeditions.

An Lushan Rebellion

Primary cause: Rebellion against repressive government, territorial expansion

The An Lushan Rebellion was a devastating rebellion against the Tang Dynasty of China that began when general An Lushan declared himself emperor in Northern China, thus establishing a rival Yan Dynasty. The rebellion followed a period of political turmoil and a series of revolts which evolved into a bloody period of conquests for territory and political rule. Religion was not a factor.

Chinese Civil War

Primary cause: Political ideology (Communism vs. Nationalism)

The Chinese Civil War was a civil war in China fought between forces loyal to the Republic of China and forces loyal to the Communist Party of China. It began in 1927 and essentially ended when major battles ceased in 1950. The war represented a split between political parties – the Communist CPC and Kuomintang’s brand of Nationalism – and did not involve religious differences at all.

Russian Civil War

Primary cause: Political ideology

The Russian Civil War began immediately after the Russian Revolution of 1917 as many political factions battled to determine Russia’s political future.  Religion was not an issue in the conflict.

Napoleonic Wars

Primary cause: Expansion

The Napoleonic Wars were a series of wars pitting the French Empire against an array of European powers. Initially France rose quickly as Napoleon conquered much of Europe but collapsed just as fast after the disastrous invasion of Russia in 1812. Ultimately, Napoleon was defeated in 1814, and sent into exile on the island of Elba; he then escaped and returned to power, only to be defeated at the Battle of Waterloo, and was exiled again, this time to Saint Helena. Religion played no part in his conquests.

30-year War

Primary cause: Religion

Finally, after almost a dozen more-destructive wars, we reach a conflict that could be considered initiated by religious differences. The war began when the King of the Romans, the new emperor of the Holy Roman Empire, Ferdinand II, tried to impose religious uniformity on his domains, forcing Roman Catholicism on its peoples. In reality however, the conflict only began due to religious differences. As the war grew, more nations joined for political or territorial conquest reasons which drove the death toll into the millions.


Of the remaining eight wars in the Top 20 (in terms of loss of life), only one, the European colonization of America, could religion even remotely be considered a factor in the conflict. Despite textbook lessons that the war started after Europeans left their homes seeking religious autonomy, the conflicts really began much earlier as a result of European’s desire to expand into the New World. Most will argue that the root cause of the European conflicts was expansion, not religious freedom.

The fact is, research shows that more than 90% of the wars and major conflicts to date were caused by factors other than religion.

Yellow Turban Rebellion

Primary cause: Peasant revolt

Second Congo War

Primary cause: Expansion


Primary cause: Lack of resources

Hundred Year’s War

Primary cause: Conflict between rulers of France

European colonization of America

Primary cause: Religious and political freedom

French Wars of Religion

Primary cause: Factional disputes between aristocratic houses of France

Shaka’s conquests

Primary cause: Expansion

War in Afghanistan

Primary cause: Military coup