Owing to the numerous conversions to Islam which followed the Turkish conquest, the Mahommedan population of the Peninsula is largely in excess of the purely Turkish element. More than half the Albanian nation and 35% of the inhabitants of Bosnia and Herzegovina adopted the creed of the conquering race. Among the Bulgars and Greeks the conversions were less numerous. The Bulgarian Mahommedans, or Pomaks, who inhabit the valleys of Rhodope and certain districts in northern Bulgaria, are numerically insignificant; the Greek followers of Islam are almost confined to Crete. The whole Moslem population of the Peninsula is about 3,300,000. The great bulk of the Christian population belongs to the Orthodox Church, of which the oecumenical patriarch at Constantinople is the nominal head, having precedence over all other ecclesiastical dignitaries. The Bulgarian, Servian, Montenegrin and Greek churches are, however, in reality autocephalous. The Bulgarian church enjoys an exceptional position, inasmuch as its spiritual chief, the exarch, who resides at Constantinople, controls the Bulgarian prelates in European Turkey as well as those in the kingdom of Bulgaria. On the other hand, the Greek prelates in Bulgaria are subject to the patriarch.
Religious and political questions are intimately connected in eastern Europe. The heads of the various religious communities are the only representatives of the Christian population recognized by the Turkish government; they possess a seat in the local administrative councils and supervise the Christian schools. The efforts of the several branches of the Orthodox Church to obtain a separate organization in the Turkish dominions are to be attributed exclusively to political motives, as no difference of dogma divides them. The Serbo-Croats of Dalmatia, and Croatia-Slavonia, some of the Gheg tribes in Albania, about 21% of the Bosnians, a still smaller number of Bulgarians in the kingdom and in Macedonia and a few Greeks in the islands belong to the Roman Catholic Church. A certain number of Bulgars at Kukush in Macedonia and elsewhere form a "uniate" church, which accepts the authority and dogma of Rome, but preserves the Orthodox rite and discipline. The Armenians are divided between the Gregorian and Uniate-Armenian churches, each under a patriarch. The other Christian confessions are numerically inconsiderable.
The Gagaüzi in Eastern Bulgaria, a Turanian and Turkish-speaking race, profess Christianity.
Until comparatively recent times Turkish and Greek were the only languages systematically taught or officially recognized in the Balkan lands subject to Turkish rule. The first, the speech of the conquering race, was the official language; the second, owing to the intellectual and literary superiority of the Greeks, their educational zeal and the privileges acquired by their church, became the language of the upper classes among the Christians. The Slavonic masses, however, both Servian and Bulgarian, preserved their language, which saved these nationalities from extinction. The Servian dialect extending into regions which escaped the Turkish yoke, enjoyed certain advantages denied to the Bulgarian: in free Montenegro the first Slavonic printing-press was founded in 1493; at Ragusa, a century later, Servian literature attained a high degree of excellence. Bulgarian, for nearly four centuries, ceased to be a written language except in a few monasteries; a literary revival, which began about the middle of the 18th century, was the first symptom of returning national consciousness.
The Servian, Bulgarian and Rumanian languages have borrowed largely from the Turkish in their vocabularies, but not in their structural forms, and have adopted many words from the Greek. Modern Greek has also a large number of Turkish words which are rejected in the artificial literary language. The revival of the various Balkan nationalities was in every case accompanied or preceded by a literary movement; in Servian literature, under the influence of Obradovich and Vuk Karajich, the popular idiom, notwithstanding the opposition of the priesthood, superseded the ecclesiastical Russian-Slavonic; in Bulgaria the eastern dialect, that of the Sredna Gora, prevailed. Among the Greeks, whose literature never suffered a complete eclipse, a similar effort to restore the classical tongue resulted in a kind of compromise; the conventional literary language, which is neither ancient nor modern, differs widely from the vernacular. Albanian, the only surviving remnant of the ancient Thraco-Illyrian speech, affords an interesting study to philologists. It undoubtedly belongs to the Indo-European family, but its earlier forms cannot, unfortunately, be ascertained owing to the absence of literary monuments.
Certain remarkable analogies between Albanian and the other languages of the Peninsula, especially Bulgarian and Rumanian, have been supposed to point to the influence exercised by the primitive speech upon the idioms of the immigrant races.