May 7, 1274: The Second Council of Lyons convenes with the goal of reunifying the Roman and Greek churches. Orthodox delegates agreed to recognize the papal claims and recite the Creed with the filioque clause, but the union was fiercely rejected by the majority of Orthodox clergy and laity fiercely rejected the union (see issue 54: Eastern Orthodoxy)

May 7, 1605: Russian prelate Nikon, patriarch of Moscow and the head of the Russian church, is born in Valdemanovo. When he tried to reform the church ...