What does nationalism have to do with World War 1?

the answer is

Nationalism was a prominent force in early 20th century Europe and a significant cause of World War I. Nationalism is an intense form of patriotism or loyalty to one’s country. Nationalists exaggerate the importance or virtues of their home country, placing its interests above those of other nations.

both believe in many god or polytheism

both built temples that they worshiped in both civilization's god were humanoid

both groups made religion a large portion of their lives

both believe in one religion throughout

the dead were buried with items for the afterlife

austria

hugary

yugoslavia

czechoslovakia