Eastern Europe is a veritable mosaic of religious communities. In this belt of countries, stretching from the Baltic to the Adriatic and Black Seas, four great clusters of religious communities meet -- and collide. Eastern Orthodoxy, Roman Catholicism, Islam, and Protestantism vie for the loyalty and adherence of, and even provide identity to, the rainbow of nationalities who have migrated, settled, and subjugated one another; who pursued or were pursued, then migrated again; who lost, gained, and again lost territories. These encounters are generally outside the pale of interest of the conventional historians in the West but are subject to endless squabbling and distortion by historians of the East. In the West the stories of these encounters bring about confusion or neglect. In the East they raise passion, hatred, and even wars, as each group views the events of the past and the present through incompatible lenses and contradictory accounts of the past that often shed more heat than light.  Winston Chur chill once allegedly said about the Balkans that the area produced more history than it could consume, a clever insight that tends to be valid for the entire Eastern European area.
The topography described here will be drawn with bold brush strokes and will, therefore, be oversimplified. "Religious topography" refers to a map of the areas where the settlement of adherents of different religious groups are colored in a specific pigment. Certain areas of Eastern Europe would tend to be solidly colored with very little of other hues present. Other areas, such as Bosnia and Herzegovina, would present a colorful, unharmonious kaleidoscope. Some countries at certain periods of their history had a variety of religions inhabiting their territories (such as Poland in the fifteenth century) but later, due to major territorial shifts, became practically uni-religious (for example, Poland after World War II). Other nations were divided religiously to a greater (such as Hungary, Yugoslavia, and Albania) or lesser (such as Ukraine, the Czech lands) degree. When a country such as Yugoslavia fell apart, its former heterogenous territory would form some homogeneous religious territories (for example, S lovenia, Montenegro, and, increasingly, Croatia) or continually heterogeneous ones (for example, Bosnia and Herzegovina, Macedonia, and Serbia, despite attempts at ethnoreligious cleansing).
The approach here is to take the political division of Eastern Europe in the late 1990's as the basis for a country-by-country survey, moving from the north to the south, starting with Poland and ending with Albania. It is the very nature of a panoramic view that generalizations abound, that many details are left out, and that careful nuancing, which is possible in monographs about each country or religion, is infeasible. Since most of the statements made here are not newly discovered, it would be inappropriate to document general observations by numerous footnotes.
The Polish people were converted to Christianity toward the end of the first millennium. In 966 C.E. Prince Mieszko accepted the Roman Catholic form of Catholicism, and this church has played the paramount role in the life of Poles ever since, to the degree that, since the nineteenth century, the equation Pole = Catholic has been commonplace. While some assume that this means Catholicism became the state religion of Poland, it would be more accurate to regard Catholicism as the national religion of Poles, because the Roman Catholic Church sometimes opposed the rulers and was able to retain a certain independence from the secular authorities and to preserve national identity.
From about the twelfth century until its partition in the eighteenth century, Poland became perhaps the most religiously tolerant country in Europe. At first, after the great Schism between Catholicism and Eastern Orthodoxy, both religions were tolerated as the Polish kings and nobility expanded the borders eastward to Ukraine. …