The priest Lech Lachowicz (72) from the district town of Szczytno (Ortel's castle) in the north-east of the country succumbed to his serious injuries in the hospital on Saturday, as the Archdiocese of Ermland in Olsztyn (Allenstein) reported.
A 27-year-old man from Szczytno is said to have brutally beaten the priest in the parish house last Sunday. He is in pre-trial detention.
The President of the Polish Bishops' Conference, Archbishop Tadeusz Wojda, condemned the violent death of the priest and demanded punishment of the perpetrator.
"There is no place for violence and brutality in a civilised and Christian society," his letter of condolence says.
Wojda called at the same time to forgiveness and mercy.