The damage at the Church of the Assumption in Piltown, County Kilkenny, was discovered Friday, two days after Christmas, the Irish Independent reported. A sacristan found red paint daubed on the front door and on the Calvary depiction of Jesus on the cross.
The graves of two of the church's former priests were also desecrated, the Rev. Pascal Moore said.
"It was an act of rage by a tortured mind," Moore said. "Whoever did this came well prepared in the cover of darkness. I am numbed by it and find it hard to find the words. It is despicable and I am sickened by it."
While volunteers labored Friday to remove the paint, Moore said repairing all the damage will cost thousands of euros.
Police had made no arrests as of late Thursday.
Pregnant Mila Kunis wins 'Best Villain' at MTV Movie Awards
Charlize Theron not engaged to Sean Penn 'yet'