Slavs
Slavs can be further grouped by religion. Orthodox Christianity is practiced by the majority of Slavs. The Orthodox Slavs include the Belarusians, Bulgarians, Macedonians, Montenegrins, Russians, Serbs, and Ukrainians and are defined by Orthodox customs and Cyrillic script as well as their cultural connection to the Byzantine Empire (Serbs also use Latin script on equal terms). Their second most common religion is Roman Catholicism. The Catholic Slavs include Croats, Czechs, Kashubs, Moravians, Poles, Silesians, Slovaks, Slovenes, and Sorbs and are defined by their Latinate influence and heritage and connection to Western Europe. There are also substantial Protestant and Lutheran minorities especially amongst the West Slavs, such as the historical Bohemian (Czech) Hussites.
Boykos
In Ukraine, the classification of Boykos and other Rusyns as an East Slavic ethnicity, distinct from Ukrainians is controversial. (The deprecated and archaic term Ruthenian, while it is also derived from "Rus'", is ambiguous, as it technically may refer to Rusyns and Ukrainians, as well as Belarusians and even Russians, depending on the historical period.) According to the 2011 Ukraine census only 131 people identified themselves as Boykos, separate from Ukrainians. However, this figure is distorted because some people otherwise identifiable as Boykos regard that name as derogatory. In the Polish census of 2011, 258 people identified their nationality as Boyko, with 14 people listing it as their only national identification.To the west of Boykos live Lemkos, east or southeast - Hutsuls, to the south or southwest - Carpathian Rusyns.