Orthodox Church of Greece (Holy Synod in Resistance)

The Orthodox Church of Greece, Holy Synod in Resistance, was a traditionalist Greek Orthodox jurisdiction following the (Julian or Old) church calendar. As with the other Old Calendarists in Greece, the Holy Synod in Resistance (often referred to with the acronym, SiR) separated from the State Church of Greece, considering it to be in error since its adoption of the secular (New or Revised Julian Calendar) calendar in 1924. It was opposed to the ecumenical movement on the grounds that ecumenism is a violation of Church teaching regarding the primacy of the Orthodox Church, though it expresses strong support for religious toleration. It did not deny that New Calendarist bodies or Orthodox involved in the ecumenical movement are with Grace, as do the other Old Calendarists in Greece, but considered them to be ailing and in error. It did not maintain communion with the New Calendarists and ecumenists. This church was in communion with the Old Calendar Orthodox Churches of Bulgaria and Romania and that part of the Russian Orthodox Church Outside Russia under Agafangel (Pashkovsky) of Odessa which did not unite with the Russian Orthodox Church in Moscow, in May 2007, forming a coalition of nearly one million traditionalist Orthodox Christians.

The last President of the Holy Synod in Resistance was Metropolitan Cyprian of Oropos and Fili (2013–14), who succeeded the previous Synod President also known as Metropolitan Cyprian of Oropos and Fili. Its hierarchy was distinguished by their theological education and publishing activities. The New Calendarist Orthodox Churches often refer to the Old Calendarists as being in schism. The Synod in Resistance described itself as "walled off" from the New Calendarists and the "right-believing flock" within the ailing Churches. The Synod in Resistance ceased to exist on March 18, 2014, when it united completely with the Church of the Genuine Orthodox Christians of Greece under the Presidency of Archbishop Kallinikos of Athens, the largest Old Calendarist Church in Greece.