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.
Demographics of Ukraine
Orthodox (includes Ukrainian Autocephalous Orthodox (UAOC), Ukrainian Orthodox - Kyiv Patriarchate (UOC-KP), Ukrainian Orthodox - Moscow Patriarchate (UOC-MP)), Ukrainian Greek Catholic, Roman Catholic, Protestant, Muslim, Jewish
Note: Ukraine's population is overwhelmingly Christian; the vast majority - up to two-thirds - identify themselves as Orthodox, but many do not specify a particular branch; the UOC-KP and the UOC-MP each represent less than a quarter of the country's population, the Ukrainian Greek Catholic Church accounts for 8-10%, and the UAOC accounts for 1-2%; Muslim and Jewish adherents each compose less than 1% of the total population (2013 est.)