The leader of the Nazi party in Germany who carried out the murder of 6 million Jews in the Holocaust in Europe was a Catholic.
When he was growing up in Lambach Austria in 1897, Hitler attended a Catholic school located in an 11th-century Benedictine cloister.
Despite understandable efforts by the Vatican to hide the facts, historians have documented that Hitler had ongoing connections to the Catholic Church (condensed here from Wikipedia):
Hitler was raised by Roman Catholic parents... Hitler... never "actually left his church or refused to pay church taxes..." The historian Steigmann-Gall states, Hitler "can be classified as Catholic."More...
...In public, Hitler often praised Christian heritage, German Christian culture, and professed a belief in an Aryan Jesus Christ, a Jesus who fought against the Jews. In his speeches and publications Hitler spoke of his interpretation of Christianity as a central motivation for his antisemitism, stating that "As a Christian I have no duty to allow myself to be cheated, but I have the duty to be a fighter for truth and justice."
Hitler, "adopted some elements of the Catholic Church's hierarchical organization, liturgy and phraseology in his politics."
According to Hitler's chief architect Albert Speer, Hitler remained a formal member of the Catholic Church until his death.... According to biographer John Toland, Hitler was still "a member in good standing of the Church of Rome despite detestation of its hierarchy, he carried within him its teaching that the Jew was the killer of God. The extermination, therefore, could be done without a twinge of conscience since he was merely acting as the avenging hand of God—so long as it was done impersonally, without cruelty."
...In 1941, according to the diary of Nazi General Gerhart Engel, Hitler stated "I am now as before a Catholic and will always remain so."