<P> In 1053 , the first step was taken in the process which led to formal schism : the Greek churches in southern Italy were forced either to close or to conform to Latin practices . In retaliation , the Ecumenical Patriarch of Constantinople Michael I Cerularius ordered the closure of all Latin churches in Constantinople . In 1054 , the papal legate sent by Leo IX travelled to Constantinople for purposes that included refusing to Cerularius the title of `` Ecumenical Patriarch '' and insisting that he recognize the Pope 's claim to be the head of all the churches . The main purpose of the papal legation was to seek help from the Byzantine Emperor in view of the Norman conquest of southern Italy and to deal with recent attacks by Leo of Ohrid against the use of unleavened bread and other Western customs , attacks that had the support of Cerularius . Historian Axel Bayer says the legation was sent in response to two letters , one from the Emperor seeking assistance in arranging a common military campaign by the eastern and western empires against the Normans , and the other from Cerularius . On the refusal of Cerularius to accept the demand , the leader of the legation , Cardinal Humbert of Silva Candida , O.S.B. , excommunicated him , and in return Cerularius excommunicated Humbert and the other legates . This was only the first act in a centuries - long process that eventually became a complete schism . </P>
<P> In 1053 , the first step was taken in the process which led to formal schism : the Greek churches in southern Italy were forced either to close or to conform to Latin practices . In retaliation , the Ecumenical Patriarch of Constantinople Michael I Cerularius ordered the closure of all Latin churches in Constantinople . In 1054 , the papal legate sent by Leo IX travelled to Constantinople for purposes that included refusing to Cerularius the title of `` Ecumenical Patriarch '' and insisting that he recognize the Pope 's claim to be the head of all the churches . The main purpose of the papal legation was to seek help from the Byzantine Emperor in view of the Norman conquest of southern Italy and to deal with recent attacks by Leo of Ohrid against the use of unleavened bread and other Western customs , attacks that had the support of Cerularius . Historian Axel Bayer says the legation was sent in response to two letters , one from the Emperor seeking assistance in arranging a common military campaign by the eastern and western empires against the Normans , and the other from Cerularius . On the refusal of Cerularius to accept the demand , the leader of the legation , Cardinal Humbert of Silva Candida , O.S.B. , excommunicated him , and in return Cerularius excommunicated Humbert and the other legates . This was only the first act in a centuries - long process that eventually became a complete schism . </P>
when did the eastern and western christian churches split
when did the eastern and western christian churches split
1054
1054