The U.S. government estimates the total population at 5.4 million (midyear 2019 estimate). According to the most recent census in 2011, Roman Catholics constitute 62 percent of the population, members of the Evangelical Church of the Augsburg Confession 5.9 percent, and Greek Catholics 3.8 percent; 13.4 percent did not state a religious affiliation. There are smaller numbers of members of the Reformed Christian Church, other Protestants, Jehovah’s Witnesses, members of the Orthodox Church, Jews, Bahai’s, and Muslims. In the 2011 census, approximately 1,200 persons self-identified as Muslim, while representatives of the Muslim community estimate their number at 5,000. According to the census, there are approximately 2,000 Jews. According to the World Jewish Congress, there are approximately 2,600 Jewish residents.

Greek Catholics are generally ethnic Slovaks and Ruthenians, although some Ruthenians belong to the Orthodox Church. Most Orthodox Christians live in the eastern part of the country. Members of the Reformed Christian Church live primarily in the south, near the border with Hungary, where many ethnic Hungarians live. Other religious groups tend to be spread evenly throughout the country.