The Orthodox Church of Ukraine (OCU) and the Ukrainian Greek Catholic Church (UGCC) will celebrate Christmas on Dec. 25, instead of Jan. 7 for the second year after transitioning to the Revised Julian Calendar. Since Sept. 1, 2023, Christians of the Eastern Rite in Ukraine have been using the Revised Julian Calendar. This calendar shifts certain fixed-date religious celebrations 13 days earlier compared to the "old style." While the OCU allowed parishes to choose their preferred Christmas date during a transitional period, the majority of believers embraced the new calendar.