The Right Rev Dr Paul Colton, the Church of Ireland Bishop of Cork, Cloyne, and Ross, said he read Baptist pastor Craig Ledbetter’s remarks with “disbelief”.
“It is reprehensible, and is certainly not representative of either the God or Christianity I believe in,” Bishop Colton said.
Mr Ledbetter, head of the Bible Baptist Church of Ballincollig, Co Cork, sparked outrage when he rowed into the referendum debate.
“Homosexuality is a sexual sin, just like rape, just like adultery,” he said.
“If a rapist demanded his crimes to be recognised legally, we as a society wouldn’t allow it.
“When [same-sex marriage] is available elsewhere, you can’t force every religious group to provide it.
“We used to live in a free society. Of all people, liberals demand diversity. Now, they demand conformity. It’s wrong.”
@b2dac Well done Bishop Paul and Bishop Michael for your courageous support for Marriage Equality.— Roger Stirling (@RogerStirling1) April 19, 2015
Mr Ledbetter said he has received a flood of threatening phone calls and emails but said he stands over his comments.
“I did not want this to be seen as an attack on people,” he said. “I never wanted to offend or hurt anybody. I care about people. I don’t condemn them or judge them.
“But you can’t be afraid to say that something is wrong. Homosexual sex is out of the bounds of God’s design for man and woman.”
However, Bishop Colton, who last year spoke out publicly in support of civil same-sex marriage, strongly criticised the pastor’s comments.
“Such language of sin and crime about homosexuality stems, it seems to me, from an uncritical and literalist approach to the Bible which, for the modern person, would make it impossible for most people to believe at all,” said Bishop Colton.
“I have no doubt that most reasonable people, not only gay and lesbian people, will be outraged by what has been said. I think they’ve every right to be.”
Last year, Bishop Colton told those at the launch of Cork’s LGBT awareness week that, whatever about his own personal views, it was undeniable that he is part of a religion and institution that has caused deep hurt and damage to gay people over the centuries.
He said if the referendum passes in May, it will simply enable the State to make provision for the marriage of people of the same gender within the State’s own framework.
“Churches, such as the Church of Ireland, will continue to have their internal regulation,” he said.
“The time may, however, come — and personally I hope it does — when the Church of Ireland will review this discipline, in the same way that some of our sister churches have done.”
Mr Ledbetter, who has lived in Ireland for over 20 years, also criticised what he said was a lack of balance in the referendum debate, and said he will be voting no.