The paper tries to explore the relation between religion and war. Although they may seem as two opposite notions many historical events have shown their cooperation. Early societies have expressed functional and integrative role of religion. The holy books of the great monotheistic religions do not call for a participation in war conflicts, but their adherents change their teachings when they become aware of ideological interests. With that they are trying to give conflicts religious justification. Religion is often misused by nationalistic politics that try to utilize religious memories for awakening collective memories. Collective memories soon turn into collective actions that further lead to war. On the area of the former Yugoslavia we have the example of nationalistic politics that manipulates with collective memories and involves religion identity into a war conflict. This paper follows Serbo – Albanian conflict on Kosovo that is primarily an ethnic one with some religious elements in it.