Could a newly-discovered collection of apparently ancient books known as the "lead codices" change our entire understanding of Christianity? The BBC's Middle East correspondent Kevin Connolly went to see the collection and then filed a report for Monday's Today programme on Radio 4. The answer, he concluded, was no. He couldn't find a single expert to give any credence to the "discovery." Indeed, he said, there is a huge market for faked antiquities in the Middle East. "There are enough fragments of the true cross to make a wooden aircraft carrier".    

It's a strange image, and curiously precise. An aircraft carrier - not a frigate.  And a wooden one - rather hard to imagine. I wondered how many fragments of the true cross it would take to make an aircraft carrier - and how the normally-meticulous Kevin Connolly had researched this fact.   

He hadn't of course. He had grabbed an old piece of folklore and repeated it as if it were a fact. My guess is he was reaching for a phrase from the Protestant reformer John Calvin, who remarked sarcastically in his Treatise on Relics that if all the supposed fragments of the true cross were put together they would fill a large ship.   

Why does this matter? There are surely worse crimes alleged against reporters than using a lazy image in the middle of a fairly inconsequential report. But it does matter - because it offers a groundless supposition in the guise of a fact. And that myth is not harmless. In this case it makes Christians look credulous.   

Over the past few weeks the media has been in its perennial summer season of self-obsession. This year's focus has been on the invasion of privacy by phone hacking, and the collusion of journalists with police and politicians. It is a serious business. But I'm not sure which part of it we are supposed to find surprising. There have always been some wealthy people ready to use their money to buy influence. There have always been a few corrupt police. And there's a reason why journalists are called "hacks."  

But while the public conversation focuses on the dubious practices of some tabloid journalists something else has been going on further up the media market. Multi-award winning writer Johann Hari has been suspended by The Independent pending an investigation. He is alleged to have spiced-up his interviews with "quotes" that were either borrowed from other sources or completely made up. And this week the veteran interviewer Lynn Barber was successfully sued for libel and malicious falsehood over a book review she wrote for The Daily Telegraph. These are two very senior broadsheet journalists who appear to have been lying. Not hacking voicemails or invading privacy or paying for stories. Just making stuff up.   

Journalists throughout history have used undercover means to get at the truth. That's their job. Yes, we need to re-examine the limits of acceptability in this. And we as consumers need to ask ourselves why we have (literally) bought into the invasion of privacy of minor celebrities and murder victims.  But we mustn't allow journalists to be hindered in exposing corruption and injustice.

But much more important is the primacy of truth, factual accuracy, integrity - call it what you will. The great newspaper proprietor CP Scott wrote that "A [newspaper's] primary office is the gathering of news. At the peril of its soul it must see that the supply is not tainted." So please don't tell me how Amy Winehouse died or what motivated Anders Breivik unless and until you know for sure. In fact, don't bother to tell me how Amy Winehouse died at all. It's none of my business. For journalists, and for Christians, facts are sacred, like fragments of the true cross on which the hope of the world lives or dies. If you pretend you have one when you know you haven't, you are not just fooling yourself - you are devaluing the only currency that really matters. 

Andrew Graystone, director of the Church and Media Network