Orientales Omnes Ecclesiae

Orientales omnes Ecclesiae (December 23, 1945) is an encyclical of Pope Pius XII to the faithful of the Ukrainian Greek Catholic Church. It commemorates the three hundred and fiftieth anniversary of the Union of Brest.

In his encyclical, Pope Pius XII explains that many trials and persecutions took place in the last three hundred and fifty years, but that the Ukrainian Greek Catholic Church always came out strong. He reminds of the many favours and assistances the Church received from Rome and how his papal predecessors always supported the independent culture and rite of the Oriental Church. In the last part of the encyclical, he addresses the grievances facing the Ukrainians in 1945. Aware of the persecution of the faithful and expects even more:

• We know that grievous are being set for your faith. We have reason to fear, that in the near future still greater hardships will befall those who refuse to betray their sacred religious allegiance.