Ah, it doesn't get better than this – Stephen Fry is being investigated for blasphemy. Where to start?

Fry is a National Treasure, a brilliant comic talent who has won huge sympathy with his honesty over his mental illness. He's also gay, and has absolutely no sympathy with the sort of rancid homophobia purveyed by some sections of the Christian community. This may have contributed to his fiery denunciation of divinity on Gay Byrne's show in 2015, when – asked what he would say to God at the pearly gates – he replied he would say: 'How dare you create a world in which there is such misery?... It's not right. It's utterly, utterly evil. Why should I respect a capricious, mean-minded, stupid god who creates a world which is so full of injustice and pain?'

He added: 'The god who created this universe, if it was created by god, is quite clearly a maniac, an utter maniac, totally selfish.'

His words arguably fell foul of Ireland's 2009 Defamation Act, which prohibits prohibits the 'publishing or uttering [of] matter that is grossly abusive or insulting in relation to matters sacred by any religion, thereby intentionally causing outrage among a substantial number of adherents of that religion'. The action must be deliberate: the offender must also intend 'to cause such outrage'.

However, there is more to the potential prosecution than meets the eye. There have been no prosecutions for blasphemy since the law was introduced. The person whose complaint forced the police to take up the issue admitted he was not personally offended by the comment. There's a widespread consensus that Fry will not be prosecuted.

So what is going on?

The 2009 act was introduced to plug a legislative gap, helpfully explained by Frank Cranmer on the Law and Religion blog. The Irish constitution forbids blasphemy, but no one had defined what, legally, that actually meant. So it was added into a reform of the law of defamation at a 'fairly late stage' as a tidying-up exercise.

Ireland's Convention on the Constitution concluded in its Sixth Report, in 2014, that the offence of blasphemy should be removed from the Constitution. THis requires a referendum, however, and it hasn't happened yet despite a government commitment to do so.

What the Fry case shows is that the sooner it happens the better. Naturally, atheist organisations want rid of it, but so do Churches too: the Irish Council of Churches issued a statement in 2013 saying it was 'largely obselete' and would be better replaced by legislation against discrimination and hate crimes. It's even been suggested that the person who complained about Fry's comments might have done so to get the ball rolling again.

It's hard to see why anyone would want to keep it. But here are three reasons why blasphemy laws in whatever form are terrible, terrible ideas.

First, they are used as tools of oppression. Pakistan, where minorities including Christians are regularly hauled off to prison on specious blasphemy charges brought by disgruntled neighbours and a climate of intolerance has recently led to a suspected (Muslim) university student being lynched, cites Ireland as an example to follow. As Prof Heiner Bielefeldt, UN special rapporteur on freedom of religion, told Atheist Ireland: 'Those countries that continue to have an intimidating anti-blasphemy practice like to quote European countries to unmask Western hypocrisy.' A blasphemy law, which forbids speaking against a particular religion or creed, is fundamentally incompatible with human rights (as legislation that forbids hate speech or incitement to violence, including religious violence, is not).

Second, they're theologically misguided. The idea that a particular creed can be enforced on a population by law, or that any expression of dissent from the religious norm should be punished, is a horrific abuse of both state and religious power. It is what happens when the religious authorities – of whatever religion – are co-opted by the state, and vice versa. It is an unholy marriage whose only aim is the maintenance and exercise of power. 'It's for your own good,' the religious partner will say, on the grounds that it alone possesses the spiritual truth that will guarantee access to heaven. But the result is the same: the individual's conscience is overruled on the grounds that other people know better.

That is not how truth faith works, and Christians should have nothing to do with it. Yes, it may be painful to hear attacks on our faith – especially when they're ill-informed or clearly motivated by hatred (and Fry's is in a different category). But that's a problem for us, not for Jesus – who, lest it be forgotten, willingly submitted to verbal and physical abuse far beyond anything we are likely to witness. We don't need to defend God from attacks on him; that's not how it works. Faith is voluntary and free, or it's nothing at all.

Third, attacks on faith – blasphemies, if you like – are great discussion starters. Fry's comments started a huge debate about God, evil and suffering, to which Christian commentators showed themselves fully equal (we've been doing this for 2,000 years, after all). The original video was viewed more than 7 million times. For every viewer who thought, 'Fry's so right', another may have thought, 'I wonder if Fry's right?' and looked for a Christian response.

If Ireland is shamed into getting rid of its blasphemy law by the current furore, so much the better. But it's a dead letter anyway. The real effort should go into putting pressure on Pakistan and other countries where such laws are a deadly weapon of terror to repeal theirs.

Follow Mark Woods on Twitter: @RevMarkWoods