The Rt Rev Joseph Devine, the Bishop of Motherwell, made the remarks following a case involving the arrest of two Christian pro-life campaigners who displayed 7ft banners showing aborted foetuses outside a clinic in Brighton. They were later cleared of public order offences.
The bishop said: "As other commentators have observed, such images should not be suppressed from the public consciousness any more than pictures of famine or the reality of war. If we cannot face the pictures, how can we conceive of endorsing the reality?
"I have no doubt that the publication of the photographs of the victims of Auschwitz and the Burma railway brought home the horrors of such evil catastrophes far more effectively than a million pleading words.
"Two hundred thousand abortions take place in Britain each year. Why is the pro-choice lobby so desperate to hide the truth about abortion from the public?"
The bishop's analogy was described as "utterly despicable" by Clare Murphy, spokeswoman for the British Pregnancy Advisory Service, saying: "It is deeply insulting to the millions of Jewish people who died."
A spokesman for the British Humanist Association said that it betrayed "a twisted lack of moral perspective" and that "the inflammatory language degrades political debate".
The bishop also accused the Green Party of "masquerading" as an environmental organisation, saying it was "anti-religious" and there was a perception its leader in Scotland, Patrick Harvie, was more interested in pursuing a gay agenda. Mr Harvie said the bishop's claims were nonsense.