Parishioners in Calry said that they were 'dismayed' after learning that thieves stole a chalice from the local church.
Gardaí believe the chalice, taken late at night from St. Patrick's Church, was worth around €300.
There were similar breaks-ins to two churches in Dromahair and Newtownmanor in Leitrim.
In Calry, the thieves tried to take a safe but were unsuccessful.
Mary Nicholson, who works in the nearby montessori school spotted that a window was left open at the back of the church.
She said that people were annoyed by the robbery.
She added: "I was going to work on Monday morning and saw that the back window was open.
"I knew that the church must have been broken into and I rang the guards.
"Everyone is dismayed to hear that they are now breaking into churches. It's disappointing. It's not a nice thing to happen."
A young woman living close-by said: "I think that it is terrible that they are attacking churches now.
"The guards called to our house looking to see if anyone had seen anything.
"I heard later that the churches in Dromahair and Newtownmanor were broken into too."
Another neighbour said that it appeared the gang responsible were not local.
He added: "Nobody saw anything on the night of September 8th.
"I was out early on the following Monday morning but there was no sign of anything.
"There are lots of robberies happening now unfortunately - it is a pity that they are targeting churches though."
Another parishioner said he believed that the thieves had mistakenly thought they were at Calry church on The Mall, which hosted a fetes that day.
"There would have been money at that," he added.
In St. Patrick Church, Dromahair, thieves managed to get in through an office, however they took nothing.
The Church of Mary, Mother of God, Newtownmanor is around ten kilometres from Dromahair.
Here, thieves disabled and removed the CCTV system before making off with two wrought iron candle sticks.
Gardaí said that they are looking into the possibility that the break-ins on the night of September 8th were related.
They added that their enquiries are ongoing and no suspects have been arrested yet.