The Constitution of Slovakia guarantees freedom of religion. In 2011, 62.0% of Slovaks identified themselves as Roman Catholics, 8.9% as Protestants, 3.8% as Slovak Greek Catholic Church, 0.9% as Orthodox Christianity, 13.4% identified themselves as Atheism or non-religious, and 10.6% did not answer the question about their belief. In 2004, about one third of the then church members regularly attended church services. The Slovak Greek Catholic Church is an Eastern rite sui iuris Catholic Church. Before World War II, an estimated 90,000 Jews lived in Slovakia (1.6% of the population), but most were murdered during the Holocaust. After further reductions due to postwar aliyah and assimilation, only about 2,300 Jews remain today (0.04% of the population).. What was the most popular religion in Slovakia?