Well name a war that was not started over religious differences. All the big ones were. I'm not talking specifically about Islam, I'm talking religion. I'm sure you know of a man called Galileo.
OK just doing the last 100 years of conflicts not involving religion. (And skipping all the civil wars even those where other nations has intervened.)
The Second Rif War
Second Franco-Moroccan War
The Italo-Turkish War
The First World War
The Georgian-Armenian War *
The Polish?Ukrainian War *
The Polish?Czechoslovak War *
The Hungarian?Romanian War of 1919 *
The Italo-Yugoslav War *
The Polish?Soviet War *
The Greco-Turkish War *
The Third Rif War
The Polish?Lithuanian War *
The Turkish?Armenian War *
The Soviet-Georgian War
The incident at Petrich
The Sino-Soviet War of 1929
The Japanese invasion of Manchuria
The Shanghai War of 1932
The Chaco War
The Colombia-Peru War
The Saudi-Yemeni War
The Second Italo-Abyssinian War
The Second Sino-Japanese War (later part of the second world war)
The Changkufeng Incident
Hungarian Invasion of the Carpatho-Ukraine
The Slovak-Hungarian War
The Italian invasion of Albania
The Soviet-Japanese Border War (1939)
The Second World War
The Indo-Pakistani War of 1947
Operation Polo
The Korean War
The Invasion of Tibet (1950-1951)
The Suez Crisis
The Vietnam War
The Portuguese-Indian War
The Sino-Indian War
The Sand War
United States occupation of the Dominican Republic
Indo-Pakistani War of 1965
South African Border War *
The Six-Day War
War of Attrition
Warsaw Pact invasion of Czechoslovakia
The "Football" War
The Indo-Pakistani War of 1971
The Yom Kippur War
The Indonesian invasion & occupation of East Timor
The Libyan?Egyptian War
The Falklands War
United States invasion of Panama
The Gulf War
The Iraqi War
* Mainly territorial disputes caused by the First World War.
Edit: What I found was that most of the disputes were about increasing territory and gain natural resources of the ones I've listed.