An investigation is under way after red graffiti was sprayed on the front of Holy Cross Church in Kenmare, Co Kerry, at the weekend.
People arriving for mass yesterday morning discovered that the front of the limestone building was sprayed with red paint, involving what appears to be a pentagram-type symbol and black writing.
Parish priest Fr George Hayes said he was shocked and disappointed and that the parish is seeking advice on how to clean the building.
Local councillor Dan McCarthy also expressed his shock at the damage, adding that generations of Kenmare people were baptised, married and attended Holy Cross, which he said was "an iconic building".
Consecrated in 1864, the church is a symbol of hope after the pandemic and people were delighted when it reopened, he said.
"It is very hard to understand the reason for this," Mr McCarthy said.
It seemed designed to upset people going into mass on a Sunday morning.
"If there is someone crying out for help, there are people who can provide help. There is great help for them. There is no need to take it out on that iconic building where people have worshiped for generations."
Councillor Patrick O'Connor said he was "shocked, saddened and outraged".

"It is a beautiful church in a beautiful town. We're not used to such things, there's very little crime and very little anti-social behaviour," he said.
He welcomed the garda investigation into the matter.
"It is really shocking for people to have to witness such vile graffiti in a place of worship, at a place of solace and refuge," he added.
Gardaí are treating the matter as an act of criminal damage and are investigating.