@AM64
One thing that I will say is don't fall for soundbites. I love the whole "religions cause all wars" sound bite which is totally ludicrous.
Nearly all of the major conflicts involving the United States had nothing to do with religion: American Revolution, War of 1812, Mexican-American War, American Civil War, WW1, WW2, Korean War, Vietnam War, 1991 Desert Storm.
You can maybe argue the recent wars in Afghanistan and Iraq because of Al Quadi/War on Terror mess. Still when it comes to total US deaths, these wars don't even fit in the grouping above. We lose more Americans every year to homicide or traffic accidents than total number of Americans that died in 20 years of military engagement in Afghanistan.
The most violent wars in human history were definitely not fought over religion. Take the top 5 conflicts in human history:
1. World War II - Land was primary factor. Hitler citied Lebensraum as the justification for war. Japan wanted natural resources not available in Japan and therefore invaded China which started off the events that led to the Pacific War
2. Mongol Invasion of China - Mongols were looking to conquer land and plunder resources. Once again, non-religion
3. World War I - Only the Ottomans cited religion in the war (calling for Jihad) and it was primarily a motivating factor rather than reason for war. Ottomans wanted back lost territories in Middle East and Balkans. The other powers either wanted land or prestige from the war. Entire Conflict was predicated on Austria-Hungary's occupation of Bosnia (Serbians wanted, once again, land)
4. Manchu Conquest of China - Land
5. Napoleonic Wars - Napoleon conquered lands in Europe for France so I would say it was a major factor although French Revolution played a part as well (and just drive for one man's glory).
National Pride/Prestige also seems to cause a lot of wars. Religion is often just used as a tool to get more support for the war and is often not the reasoning behind the war or even a war aim.