It may be assumed that on the Balkans, maybe more than anywhere else in Europe, people's religious affiliation and ethnicity are a constituent part of their identity. Historically speaking, for instance, the nation was changed once the religion was changed. Thus, for instance, when an Orthodox Serbian, in given historical circumstances, accepted Catholicism or, more often, Islam, he actually left the Serbian ethnic group. Even when he himself did not insist on that, his former ethnic group rejected him. The controversies which comprised religious differences, that is, the churches and religious communities, became a constituent part of the lives of individuals and nations. As religion was the basis for differences, so it was also the basis for understanding, collaboration, development of solidarity and friendship. Religion, that is, historical churches on this territory, was often the basic integrative form upon which the state was built and sustained in the Middle Ages. The churches are older than the present states and they brought into them whatever was positive or negative in their historical experience. Surely, this was not done by decrees or legal regulations (though they were abundant in many forms), but primarily by means of tradition, culture and consciousness of individuals and nations. This process was - and still is - crucially affected by religion. Therefore, the religious sphere is of exceptional importance for understanding many historical currents, namely, the events that took place - and are taking place or will take place - on this territory in the near future. That is why religion or the church is the place which often crucially affects our fate not only by prayers to God but by promoting intolerance to other people as well as by stimulating love, understanding and acceptance of differences between people.