The schism, which started in 2014 after the annexation of Crimea, has only deepened after last year’s full-blown invasion.
Centuries of tradition are another casualty of this war.
But as they watched outside on big screens, worshippers reflected on what they have lost in this year of violence.
“It’s really hard to celebrate the birth of Christ when a lot of Ukrainians are dying, especially children, and also my friends and my classmates,” says a worshipper called Natalya.
This has been unbelievably shocking and difficult year for Ukraine.
Vladimir Putin’s war of aggression has broken families and caused immense pain.
In Moscow, the Russian leader looked uncomfortable as he posed for state television at a service inside the Kremlin.
Isolated and heavily sanctioned, the war he started shows no sign of ending and the festive ceasefire he commanded has been dismissed as propaganda.
But in Ukraine, there’s hope with people praying for a swift victory and the return of their occupied lands.