"Originally, all Unitarians were Christians who did not believe in the Holy Trinity of God (Father, Son, and Holy Ghost). Instead, they believed in the unity, or single aspect, of God. Although people have held Unitarian beliefs since the time of Jesus’s death, religious groups did not form around these ideas until the mid-1500s in Transylvania and the 1600s in England. Religious authorities at this time saw early Unitarians as heretics and often persecuted them. Important figures from this period include John Biddle, Francis David, Michael Servetus, King John Sigismund and Faustus Socinus.