A fire at Drumcree church near Portadown in County Armagh is being treated as malicious, police have said.
The attack happened at Drumcree church
A tin of paint was set alight at the back of the building at about 0500 BST, causing minor damage.
The church has been in the media spotlight for the last number of years, as a result of the controversy over an Orange Order parade each July.
The nationalist Garvaghy Road Residents' Coalition has condemned the church attack as "wrong".
A spokesperson said: "Nothing can justify this attack on Drumcree church.
"Irrespective of the very justifiable anger which exists as a result of the Parades Commission decision not to class next week's Orange march and rally as contentious, and its failure to impose any restrictions in that march, this attack was wrong.
"The Garvaghy Road Residents' Coalition would ask that there is no repetition of this attack on Drumcree church."
Each July, the Portadown Orange Lodge attends a service at Drumcree church to commemorate the anniversary of the Battle of the Somme.
Since 1998, their homeward route, along the mainly nationalist Garvaghy Road, has been blocked by the security forces, following a determination by the Parades Commission.
The commission was set up in 1997 to make decisions on whether controversial parades should be restricted.
The Drumcree parade has been marked by serious violence in the past, but it has passed off peacefully in the last three years.
The march has been one of Northern Ireland's most contentious. The route was last used by Orangemen in 1997.