The Catholic Bishop of Paisley has hit out at an hour-long documentary on the Pope presented by controversial gay rights campaigner Peter Tatchell.

In the programme, which airs tonight, Tatchell suggests among other things that the Pope was involved in a cover-up of child sex abuse cases, and that he sympathises with the beliefs of Holocaust denier and suspended bishop Richard Williamson, whose excommunication was lifted by the Pope last year.

Bishop Philip Tartaglia said Tatchell’s past assertion that “not all sex involving children is unwanted, abusive or harmful” cast “huge doubt on his claim to be an expert on human sexuality or a credible critic of the Pope or of the Catholic Church”.

He admitted that the child abuse scandal had been “catastrophic” for the Catholic Church, but insisted that the Pope “has done and is doing everything possible to punish the perpetrators, console the victims and repair the damage”.

He said it was “disturbing” that Channel 4 had given Tatchell an hour-long prime time programme “in which to attack the Pope and the Catholic Church” and said the programme’s content showed that the campaigner knew “next to nothing about the real nature and mission of the Catholic Church”.

The programme has also come under attack from Damian Thompson, former editor of the Catholic Herald and current Blogs Editor for The Telegraph.

Writing in The Telegraph last week, Thompson said the programme twisted the truth and “doggedly misleads” the audience.

He said it was a “smear tactic” on the part of Tatchell to claim that the Pope had rescinded Williamson’s excommunication because he believed his views to be acceptable, and that Tatchell had made no attempt to understand Catholic doctrine on issues like birth control or abortion.

He writes: “I know that Tatchell profoundly disagrees with Catholic teaching. Fair enough. But I also thought he had enough integrity not to misrepresent key concepts such as papal infallibility, which he implies means that no decision of the Pope can be questioned – a schoolboy error.

“Tatchell also claims that the Pope’s previous role as Prefect of the Congregation for the Doctrine of the Faith gave him control over Church doctrines.

“That last statement is so ignorant that I could hardly believe I was hearing it. Did Channel 4 not employ any researchers for this project?”

The Trouble with the Pope airs on Channel 4 at 8pm, Monday 13 September.