Attacks on priests are "a symptom of a fundamental shift towards a culture of violence and aggression", a spokesman for the Catholic Church has said.
Fr Tim Bartlett was speaking after three priests were robbed in two separate incidents at the weekend.
Two priests were robbed at knifepoint in Cookstown on Monday and a third priest was robbed in west Belfast.
First Minister Ian Paisley condemned the robberies and called for swift action to bring the thieves to justice.
Fr Bartlett, secretary to the Church's Commission on Social Affairs, said: "Priests, by their nature and vocation, are prehaps perceived to be more likely to be trusting, rather than concerned about their own security.
"Sometimes this can make them more prey to such attacks."
Priests are generally encouraged to keep their security under review but he said there was no move to change the policy of keeping churches open, as places of prayer and spiritual refuge.
Fr Bartlett said there had been a general increase in such attacks, but it would be wrong to exaggerate it.
Mr Paisley said: "I hope that quick action will be taken to bring those, who brought about these acts, to the law and that they will pay the price for their breaking of the law," he said.
In Cookstown, two men broke a window in the house at Convent Road where the two priests lived at 0245 GMT on Monday.
They ransacked downstairs and woke one of the curates, threatening him with a knife before taking cash and a car.
Father Liam McKinney was sleeping when the thieves woke him.
"My bedroom door burst open. There were two young men in their early 20s. They demanded money, a knife was produced and I was led down to the other priest's bedroom," he said.
"In many ways, you are trying to watch the knife. You don't know what is going through your mind. It is a mixture of fear and adrenaline. It was an experience that I hope never to have to repeat."
The thieves took £400 and one of the men's car. One of the priests managed to break away from the robbers and raise the alert.
The priests have strengthened their security following the robbery.
In west Belfast, a priest was returning to St John's Presbytery at the weekend, when the thieves took money from a charity collection.
In September, another priest was assaulted during a burglary at a parochial house in County Down.
The priest, believed to be retired, was asleep upstairs in the house at Drumnaconagher Road, Crossgar, when he was awoken by an intruder who pushed him to the ground. He suffered a cut to the head.
The intruder then fled. A number of rooms had been ransacked and money was stolen.