NOT for the first time, I'm puzzled.

The conundrum has bothered me for years. Those who devote themselves to knotty little theological arguments would probably call me crass, or say I’m being wilfully obtuse. Still, answer me this: how is it that men who take vows of celibacy become experts on the institution of marriage?

How is it, for that matter, that such men are obliged to become celibate in the first place? And how does their strenuous, life-long avoidance of sexual activity translate into the conviction that certain varieties of fooling around favoured by others are forbidden by God?

Someone should show me a sign. Instead, I get press releases. Most of these emanate currently from the Roman Catholic Church in Scotland, but that’s largely because – who do I thank? – this is not America, where our RC hierarchy would be marked down for wimpishness. Religious fundamentalism has yet to overrun our politics.

Instead, we have a cardinal, an archbishop and a bishop predicting society’s ruin if Scots of the same gender are allowed to marry. A composite rendering of recent impassioned statements by Cardinal Keith O’Brien, pictured, Archbishop Mario Conti, and Bishop Philip Tartaglia runs something like this.

Scotland would be shamed; a universal human right would be subverted; the unions would be “meaningless”; the common good would be undermined; religious intolerance would be incited; the lie that “human nature” can be “rewritten” would spread; and the very institution of marriage would be under “direct attack”. Such is the view of three celibate men who are, of course, forbidden to marry.

Cardinal O’Brien has had a lot to say in recent times about “aggressive secularism”. He’s against it, aggressively. No doubt he believes a 14-week Scottish Government consultation on a proposal to extend a right to gay people is yet another atheistical plot. What he fails to stress is that no-one – no-one – wants to force any church to conduct same sex marriages. If this is a plot, it’s pretty feeble.

But then, if such is the case, the reaction from O’Brien and his colleagues is on the noisy side of energetic. Nothing is being imposed on their church, yet they intend to “vigorously oppose” any legislation. Were I the mischievous sort, I’d say they were in the business of enforced conversion. What else would you call it? Their line on homosexuality and same-sex marriage amounts to this: it doesn’t matter what you think, feel, or believe, you will live out your life as our church decrees, Catholic or not. Fair enough?

After the thunder fades and the lightning bolts sputter to Earth, another omission is noticeable. That would be Scriptural justification. For gay rights campaigners, this is familiar turf, but still worth bearing in mind. The celibate trio speak in Christianity’s name. So what did Jesus have to say about same-sex unions? The cardinal knows the answer: nothing at all. The New Testament is utterly silent about celibacy, too, and – perhaps because of all the female priests active in the early church – about the ordination of women.

In short, none of this has anything to do with Jesus. Biblical authority for the attitudes of Catholic princes (and others) towards homosexuality derives from a few stray remarks by St Paul and, always, the Old Testament, that model of clarity and consistency, the section of the Bible favoured by literalists and fundamentalists. There’s plenty there, to be sure, about gays.

Much of it comes from Leviticus, that handbook on ancient Jewish ritual. There’s 18:22: “You shall not lie with a male as one lies with a female; it is an abomination.” There’s 20:13: “If there is a man who lies with a male as those who lie with a woman, both of them have committed a detestable act; they shall surely be put to death. Their blood guilt is upon them.”

I’d call that unambiguous. But is O’Brien calling on the Scottish Government to turn this into an Old Testament country, and to give Leviticus the force of law? That would be worth watching, if only for the by-laws on animal sacrifices. We would also have to declare menstruation “unclean”, of course, make consulting with wizards an offence, and bring back the death penalty for blasphemy. Scotland’s women should also know that giving birth involves “uncleanliness”. And Leviticus takes a very hard line on mildew: avoid at all costs.

CHEAP shots, of course, but it’s not my Bible. I’m not attempting to build social policy on archaic tribal rituals, nor am I threatening – Tartaglia’s gambit – to deny the Catholic vote to politicians who fail to exercise deference. I leave jokes about sharia law to others. Whether Scotland’s Catholics are quite as obedient in the privacy of the polling booth as the Bishop of Paisley would like to believe is meanwhile another matter.

His understanding of democratic principle is between the cleric and his conscience. The same goes for the rest of us. For those who choose to be governed spiritually, however, things become complicated. Any issue can be defined as moral, and therefore as fair game for the exercise of religious authority. Historically, the Catholic Church has not shrunk from that challenge. Even now, as the Scottish hierarchy has been busy demonstrating, it steps on secular toes whenever it sees the need. The spirit of charity moves me to say that this is a big mistake.

What happens if large numbers of Scotland’s Catholics decide that a cardinal, an archbishop and a bishop are dead wrong? The polling evidence is slight, but where same-sex marriage is concerned, this seems to be the case. Humanity speaks to humanity; people know what love means, and what it demands. Many Catholics will also know perfectly well that no-one is forcing their church to change its ways. Their own dissent will do that.

What transpired after the great controversies over birth control? What became of the Vatican’s attempts to prevent the use of condoms in the fight against HIV? Too often for the comfort of the church, common sense intervened. Too few adherents could find any echo of the teachings of Christ in these rulings. So would Jesus really have barred the door against same-sex couples?

Over in Northern Ireland, the former Bishop of Derry, Edward Daly, has invited a similar question in the argument over priestly celibacy. He is as courageous now as he was 39 years ago, during the Bloody Sunday massacre. He has no wish to abolish a celibate priesthood for those who make that choice, but he understands reality. His church is simply running out of young men prepared to take the vow and make the sacrifice. Christ didn’t ask it of them. So what is the point?

Power, mostly, and the habits called tradition. Power over human relationships, and therefore over society, purportedly – though not actually – in God’s name. If the early church had women priests, why not the modern Church of Rome?

The confusion is hardly unique. Jesus said nothing about gay relationships, yet the Kirk is riven, currently, because some gay people wish to serve as ministers. You have to prefer the fanatic Paul to gentle Christ to make sense of that. But then, some prejudices are just too useful to waste.