There are two starkly different ways of viewing the pronouncements of Cardinal Keith O'Brien over the past few years.
From the point of view of mainstream Britain, this is a man on the lunatic fringe of religious fanaticism. When he breaks off talks with the Scottish government over same-sex marriage, as he did on Sunday, compares the reform to the reintroduction of slavery, condemns it as "a grotesque subversion of a universally accepted human right", or brutally describes Scottish abortion rates as "equivalent to two Dunblane massacres a day", for many people he is completely out of order: a walking, talking demonstration of why we are grateful that religion has moved to the sidelines.
But viewed from Rome, the 74-year-old Irish-born Archbishop of St Andrews and Edinburgh is something else altogether: a prodigal son who has seen the error of his (relatively) youthful ways and returned to the path of righteousness; the most senior Catholic churchman in Britain, a man who is uncannily alert to the Vatican's concerns and finds earthy, vigorous language in which to promote its views.
The fact that his words are interpreted very differently in Britain, as the utterances, as Peter Tatchell put it, of "a sad, sick man", says a great deal about the vast mental expanse that now separates the Church and mainstream British society.
But what does it say about Keith O'Brien himself?
Nobody who knows him has any hesitation in telling you, first and foremost, what a charming individual he is. There is also no doubting the sincerity of his own religious commitment: twice rejected from the ministry because of a heart murmur, he defied those who rejected him. He has a BSc in maths and chemistry which may have been one of the things that put him on a wavelength with the late Pope John Paul II, who all his life held science in high regard. O'Brien rose rapidly through the church, peaking as Archbishop of St Andrews and Edinburgh, a job he has held for more than 25 years.
And that rapid ascent was curious. Because earlier in his career, he was quite as outspoken as he is today – but as a notorious liberal. At the Synod of Bishops, held in 1999, he insisted on raising the issue of priestly celibacy – the church's insistence that priests must be unmarried and remain unmarried for life, despite the absence of any doctrinal justification for the bar.
In 2003, despite his egregious lack of tact, he was created a cardinal. The hardliners were appalled. A group called Catholic Truth called him "a source of scandal" and said the fact that he had been made a cardinal was "shocking beyond words".
But there is a history in the Catholic Church of youthful liberals seeing the error of their ways. The present Pope was an ardent supporter of the liberal reforms of the Second Vatican Council until, like the classic liberal who has been mugged, he was terrorised by left-wing students at his university and had a Pauline conversion to extreme conservatism. Is that what has befallen Keith O'Brien?
Professor Haldane believes it was something of the sort. "He suddenly realised the focus that would be placed on absolutely everything he said, and the responsibility that came with his new position. He was now speaking for the Church, not just for himself."
A slightly less generous interpretation is also possible. Before the last conclave, some bold bookies gave him 20-1 odds of becoming pope. After his strenuous efforts over the past few years to gain a reputation for unimpeachable orthodoxy, those odds can only have improved.