Ferenc Dávid (also rendered as Francis David or Francis Davidis; born as Franz David Hertel, – 15 November 1579) was a Unitarian preacher and theologian from Transylvania, the founder of the Unitarian Church of Transylvania, and the leading figure of the Nontrinitarian Christian movements during the Protestant Reformation. He disputed the mainstream Christian doctrine of the Trinity, believing God to be one and indivisible. Studying Catholic theology in Wittenberg and in Frankfurt an der Oder, he was first ordained as a Roman Catholic priest, later he became a Lutheran minister and then a Calvinist bishop in the Principality of Transylvania. Dávid learnt the teachings and practices of the Roman Catholic and Protestant churches, but later rejected several of them and came to embrace Unitarianism. Life Early life Ferenc Dávid was born in Kolozsvár, Hungary (present-day Cluj-Napoca, Romania), to a Transylvanian Saxon father (David Hertel, who worked as a tanner) and to a Hungarian mother. The Hertel/Herthel family was an old Transylvanian Saxon aristocratic family of Kolozsvár. In Latin and Hungarian he used his name as Francis Davidis or Dávid Ferenc after his father's forename David. He had at least three brothers: Gregor, Peter and Nikolaus. Peter and Gregor inherited the job of their father in the guild. Gáspár Heltai, the father of Peter's wife Borbála, was a Protestant Reformer, Lutheran and later Unitarian minister, translator, outstanding author of the Hungarian late Renaissance era. He owned the paper mill and the press of Kolozsvár where several religious and scientific books were made in Hungarian and German. Ferenc Dávid was raised Catholic. After finishing his studies in the High School of Kolozsvár (today Cluj Napoca, Romania) he went to the Holy Roman Empire to study Catholic theology first at the University of Wittenberg and then later at the Alma Mater Viadrina (University of Frankfurt an der Oder) where he became a Catholic parson. Lutheranism In 1542 the Lutheran reformator, Johannes Honterus introduced the Lutheran doctrines to the citizens of Kolozsvár. After arriving back in Transylvania Ferenc Dávid joined the Lutheran wing of the Reformation where he became a minister and then a Lutheran bishop. He worked as headmaster of the Gymnasium of Beszterce (today Bistrița, Romania), then as Lutheran pastor in Petres (today Cetate, Romania), later headmaster of the Gymnasium of Kolozsvár and from 1555 chief pastor of Kolozsvár (today Cluj Napoca, Romania). On 1 June 1557 the Diet of Torda (National