Mark Steel: If you think Islam is medieval, look at Catholicism

Tomorrow, the Pope was meant to have visited the University of La Sapienza in Rome. Only, he won't now, having got wind of a protest which would have put the defiance of Burmese monks in the shade. The punishment for this one would have been an eternity of agonising torment.

The target of the planned demonstration, Benedict XVI, is regarded by the university's students and academics at as "anti-science". Modern church leaders usually deny that they are opposed to science, and try to find scientific explanations for Biblical ideas, such as intelligent design. So they will make pronouncements such as: "Recent fossil studies suggest there was once a species of whale in the Galilee region that had a throat the size of a modern detached house and could have been fitted with en-suite facilities and central heating, proving it is quite possible that Jonah could have lived in one fairly comfortably for several months!"

Pope Benedict faces a specific complaint, that when he was a mere cardinal, he said the trial of Galileo by the inquisition in 1633 was "Reasonable and just." The result of the trial was that, for the crime of confirming that the Earth orbits the Sun, he was sentenced to execution, although this was later reduced to permanent house arrest. This may seem harsh, so a typical modern defender of the sentence, the writer Vittorio Messori, justified it by saying: "Galileo was not condemned for what he said but the way he said it." So that was the problem – the Vatican didn't mind Galileo's theories about the Universe, but he said them with his mouth full.

The difficulty with this explanation is that Galileo's sentence fitted the Church's attitude of the time. It declared "reason" to be corrupt, which suggests that a science lesson run by 17th-century cardinals would not involve the most vigorous experiments. A teacher would say: "Right. Who can tell me why copper tends to turn green?" And if one kid put their hand up and said, "It's the reaction of the atoms mixing with oxygen in a process known as oxidisation, sir", the teacher would yell, "NO, BOY. It turns green because it's a MIRACLE."

Indeed, when the philosopher Vanini tried to find proof for the existence of miracles, this was deemed by Vatican officials to be interfering with God's will, so they cut out his tongue, strangled and burned him. Reasonable and just, because you should have heard the way he said it. The scientific discoveries of Galileo's time led to dissent with the Church. For example, there was the radical, wealthy priest, Picot. Apparently, when he was dying, he offered a fortune to any priest willing to administer his last rites without incantations, chanting or incense. One priest agreed and, soon afterwards, Picot went into a coma. After three days, the priest at Picot's bedside could resist no longer and began chanting, at which point Picot sat up and said, "I can still take away the money, you know".

But maybe the most interesting side to Benedict's defence of his 17th-century predecessors is imagining the furore if a similar attitude happened within Islam. If the leader of the Muslim world declared it was reasonable and just to have sentenced one of history's greatest minds to execution, piles of commentators would be telling us this proved Islam was a medieval, ignorant creed incompatible with Western values. So why hasn't Martin Amis written a pamphlet full of such pompous twaddle as, "Within Galileo's studies of orbits lie you, me, our knowledgification, our triumphant cleverment. So as I consider this catechismic papal assault on braininess, I feel a soulful urge to squeeze every Redemptionista into a giant confession box and set fire to the bloody lot of them. Don't you?"

Why aren't there articles by people claiming to be feminists that start, "What Catholics have to understand, if they're going to come over here from Ireland and Poland is that they should adopt our tolerant values towards gays and abortion?" Why aren't there politicians announcing that they will not speak to their constituents unless they are wearing a condom? Christopher Hitchens has compained that Islam is incapable of going through a Reformation. But not as much as Catholicism, seeing as the whole point of the Reformation was to replace it. So why isn't he demanding that we bomb Italy?

Presumably, we will soon have intellectuals insisting that the rejection of Galileo shows we are in a clash of civilisations, and the Sandinistas and the IRA and Guy Fawkes were all terrorists and Catholics, so that proves it.

The demonstrators in Rome had planned to ruin the Pope's visit by playing "very loud rock music", as he once proclaimed rock was the "work of the Devil." Sometimes the choice seems so difficult – atheism or Satanism. I just can't make up my mind.