Courtesy of Twitter @diakrisis_logismon
Q. Had the Calendar ever been an issue discussed before?
A. Yes. In the 16th century, when Pope Gregory XIII instituted the New Calendar, he wrote to the Orthodox to encourage them to accept it. They refused, and condemned the Calendar on three separate occasions. One of these Orthodox councils resulted in a document called the Sigillion of 1583, which condemned the New Calendar as incompatible with the Orthodox Faith.