The National Union of Journalists (NUJ) has criticised Ian Paisley after an online post about reporter Sam McBride.
The NUJ described it as an “unwarranted and unworthy” personal attack on a prominent political journalist.
The DUP MP for North Antrim wrote the Facebook post in response to an article by Mr McBride in the News Letter.
The article suggested the DUP had prioritised opposition to an Irish Language Act over resisting change to Northern Ireland’s abortion law.
Mr Paisley said the “Christian ethos of the DUP is under attack from the press” and referred to what he described as Mr McBride’s own Christian background and education.
The North Antrim MP argued that his party had “not been found wanting on the campaign to prevent the implementation of the most draconian abortion laws” .
It was typical of the press to “blame unionists for a decision that was not theirs”, he said.
He also strongly denigrated the News Letter journalist’s character, claiming he was “despicable… immature… and simplistic”.
Mr McBride accused the MP of making “a series of untrue allegations”, adding that while people had a right to dismiss his analysis, anything he writes was his “honest professional – not personal – opinion”.
The NUJ’s Seamus Dooley criticised Mr Paisley’s 750 word Facebook comment as a “clear attempt to smear the professional reputation of a conscientious journalist”.
Mr Dooley said the North Antrim MP had “gone beyond the bounds of acceptable political discourse and has engaged in a personal attack which is extremely damaging.”
The News Letter’s political editor also received support from a number of senior politicians.
Ulster Unionist leader Robin Swann described Mr Paisley’s attack as “extremely disappointing”.
Mr Swann said the North Antrim MP’s Facebook piece was “a clear example of where he has played the man rather than the ball”.
SDLP leader Colum Eastwood called Mr Paisley’s comments a “total disgrace” and expressed his solidarity with Mr McBride.
Alliance Party leader and MEP Naomi Long said while politicians might not always like what journalists like, a free and open press was part of democracy.
“Attacking a journalist so personally… is bullying,” she said. “Completely disgraceful.”