A man who "viciously attacked" the secretary of a parochial house, "just lost control", according to the church's parish priest.
Fr Patrick Delargy said the attack at Kirkinriola Parish in Ballymena raises "the issue of parochial houses being vulnerable".
Police confirmed on Thursday they are investigating the assault on a woman.
It happened at about 16:00 GMT on Thursday at the premises on the Broughshane Road.
The man was described as wearing a black coat, blue jeans, brown boots, a scarf and a black beanie hat.
He was riding a black bicycle.
'Opening the door is a big decision'
Speaking to BBC News NI, Fr Delargy said it was fairly common for vulnerable people to call to the property asking for assistance and this had to be balanced against safety concerns.
"The secretary and myself were in the office and I took a phone call, and there was a knock at the door," said Fr Delargy.
"She went to attend to that, there was a man who was under the influence of drink and was asking for money."
He said a buzzer system to protect the people in the house was in place, but the secretary decided to make an exception in opening the door to the man concerned.
'People can behave irrationally'
"At one stage he just lost control, and he did strike her and he started throwing things," said Fr Delargy.
"Flower pots and everything. By the time I could get out again the man had disappeared.
"It is a big decision as to whether or not to open the door or not, and one I have taken plenty of times.
"You never do know when someone is going to behave irrationally."
Fr Delargy said the secretary had been left badly shaken by the incident, but had shown composure to review CCTV of the incident and speak to police after it happened.
He said there were a number of services within the parish offered to people with alcohol or addiction issues, as well as offering short-term support.
"We must try to help people who are vulnerable and needy," said Fr Delargy. "But there are circumstances where people are not able to respond properly."