Four parishes in County Down and Antrim were broken into in recent weeks with a sum of money taken.
The thieves stole from St Malachy's Church in Hillsborough, Aghaderg Church, Loughbrickland and St John's Church, Dromara.
In County Antrim St Andrew's Church in Lisburn was targeted.
In a statement, a spokesperson for the Church of Ireland Diocese of Down and Dromore said: "Following a recent spate of robberies on church premises we have urged our clergy to be extra vigilant over the Christmas period.
"We are saddened to have been targeted in this way and hope that no further such incidents occur for us or for anyone else in this Christmas season and beyond."