A door at the back St Mary's Star of the Sea Church in Newtownabbey was set on fire using flammable liquid at some point early on Sunday morning.
The damage was discovered at around 01:30 and police were called.
Detectives say the attack was a sectarian hate crime and are appealing for witnesses.
It's not the first time the church has been damaged by criminals. Last September paint and petrol bombs were thrown at the building.
The local Alliance councillor Billy Webb told the BBC he was 'shocked and horrified'.
"No place of worship should ever be subjected to any attack. This is not the first time St Mary's Star of the Sea has become a target and this thuggish behaviour must be brought to an end.
"This latest attack on the church will sadden the parish priest, the parishioners and the local community representing all faiths. Those doing this really need to take a step back.
"This is just an attack on us all, and this campaign of intolerance must be brought to an end quickly." He said.