January 13, 367 (traditional date): Hilary of Poitiers, the leading orthodox church father during Arianism's heyday, dies. His writings about the Trinity and his organization of anti-Arian allies were influential in fighting the heresy but did not have their full effect until after his death (see issue 51: Heresy in the Early Church).
January 13, 1501: Christianity's first vernacular hymnal is printed in Prague, containing 89 hymns in Czech.
January 13, 1616: Flemish mystic Antoinette Bourignon is born. A mystical writer whose works were included by John Wesley in his Christian Library, she soon found herself estranged from mainstream Christianity, especially when she declared herself the "woman clothed with the sun" of Revelation 12. Still, her ideas were so influential that, for 178 years, ministers of the Church of Scotland had to make an explicit denial of Bouringnonism before they could be ordained.
January 13, 1635: Philip Jacob Spener, founder of German pietism, is born in Rappolstein. His emphasis on new birth and holy living revitalized the German Lutheran Church and many later movements, including American evangelicalism (see issue 10: Pietism).
January 13, 1691: George Fox, founder of the Society of Friends (Quakers), dies. Fox left the Anglican church to rely on the "Inner Light of the Living Christ."