1923. in Constantinople (Istanbul- Turkey) all prelates od Orthodox Churches in the world gathered to discuss the problem of calendar. Some of them, knowing that "old" calendar is incorrect tryed to enlade that Rymo-catholic Pope Gregory IV was right when he changed the calendar in the western world. Acctually, there was no big change, he just moved it for 13 days, plus that each 4th year has 366 days.
Prelates of Church in Greece, Romania, Bulgaria accepted the change, knowing that in case they do not do so, there might come to total brakedown in holiday order to the point that it all might get confused so Easter would be in Monday(for example).
One friend of mine sent me e-mail....regarding his interest in the same subject, sending me some relevant informations about this issue.
Here are the facts:
Gaius Iulius placed year with 366 days in his calendar, but each hundred years that can be multipied with 400 (800, 1200...)except the millenium year (2000, 4000)
In the beggining...when new Gregory`s calendar was invented difference between Julius`s and Gregory`s calendar was 10 days but during the time past....difference between calendars came to number 13. So 2101 christmass will be on january 8th and new year will be on january 14th.
Ivan also says that he gathered those informations from military enciclopedia...so if it`s lying he is lying as well...but i doubt so.
Serbian prelates (that did recommened the change) did not bite. That for, in orthodox world we have Churches that do use the calendar created in time of Pope Gregory, while Russian and Serbian Church still use caledar created long time ago, accurately in the time of Roman Emperor Julius Ceasar.