I hope and pray that it isn't true. Fr Tom Uzhunnalil, 56, was kidnapped by Islamic State militants in Yemen during their attack on an old people's home. He was, if news reports were to be believed, scheduled to be crucified on Good Friday, and various reports since then have said the sentence was carried out.

And that's the point: if they were to be believed. 

The allegations, which appear to have originated in a Facebook post by the Franciscan Sisters of of Siessen in South Africa (since deleted) were shared round the world and widely reported as fact, even by reputable news outlets. This is in spite of the lack of any kind of corroboration for the original rumours and repeated denials from everyone who was actually in a position to know that any information whatsoever had been received about the missing priest. 

Just to be clear, those denials have since been repeated: Bishop Paul Hinder, head of the Apostolic Vicariate of Southern Arabia, told the Catholic News Service yesterday: "I have no confirmation that anything happened Good Friday." He added that the rumours appeared to be untrue.

When they first surfaced, Christian Today took a decision not to report them, because it was obvious how thin they were.

That sort of thing just feeds the beast. The internet is better off without it. It's the ultimate in irresponsible journalism, not least because – and this ought to stop all those who clicked 'like', 'share' and 'retweet' on all those lurid stories from sleeping at night – if this act of barbarism was carried out, the media-savvy Islamic State might just have got the idea from all those concerned Christians.

So why did this story get so much traction, and why are so many people so keen to believe it?

1. Because it gets clicks. If you're an online news outlet, you need people to read what you write. A headline about ISIS threatening to crucify a priest is irresistible, whether it's based on fact or not.

2. Because it fits a narrative.Yes, Islamic State is bad enough. It has done terrible things (though Bashar al Assad's government has done things just as bad) but if it were to crucify a priest it would fit the narrative of pure, Satanic, irredeemable evil. It is convenient to believe the worst of your enemy; it justifies whatever you want to do to him.

3. Because it bolsters a position. Some of those commenting on the crucifixion story used it to back their arguments against allowing Muslim refugees into Europe or the US. "These people" crucify priests, was the claim. It's absurd, but it's out there.

4. We like to be shocked. Too grim? Perhaps. But we do click on stories that we know will horrify us. Partly it's because we genuinely believe we need to know. Partly it's because of a darkness in our souls: we are terribly sorry for the person suffering, but even more terribly glad it isn't us.

5. We really do care. We need to be honest about our motivations for reading and sharing stories like this, and admit that not all of them are very good ones. But as well as feeding a narrative of Christian persecution and Muslim demonization, we're responding in a visceral way to the profaning of the central image of our faith: Christ on a cross. We feel deeply for Fr Tom Uzhunnalil, but we feel this as an attack on our faith, too.

We know ISIS is capable of anything. It has burned people to death. Another kidnapped priest was ransomed by his family and returned to them in a box – in pieces. The crucifixion story is grotesque, but – tragically – it is not incredible.

It may yet, in spite of its wafer-thin provenance, turn out to be true. That doesn't negate anything I've said.

We shouldn't believe stories just because they cast Muslims in a bad light, or back up our prejudices about immigration or refugees or whatever. We shouldn't share a story like this, that's profoundly distressing to Fr Tom's family and friends, if we aren't absolutely sure it's true. We shouldn't pander to our dark side by taking a vicarious pleasure in deeds of evil.

We should pray for Fr Tom – and for his captors, and for everyone who's in the grip of evil. And we should be lovers of truth.

Follow Mark Woods on Twitter: @RevMarkWoods