There's a story going round at the moment about a 'prophecy' that God will remove North Korean dictator Kim Jong Un unless he becomes a Christian.

The prophetess in question is one Cindy Jacobs, and a video of her in action was shared on Right Wing Watch, a whistleblower site that is no friend to evangelical Christians.

Well, God bless Cindy. She seems like a nice person. But I'll be honest: I watch things like that with my hands over my eyes, wincing at every second sentence. Because, not to put too fine a point on it, I don't believe it. I don't think Ms Jacobs – with all her undoubted sincerity – has a hot line to God. I think the chances of Kim being converted are vanishingly small, and so are the chances of him being removed from power. How do I know? I don't, but I read the papers, and that's my best guess. With respect, I don't think Ms Jacobs can do better.

This way of thinking and talking about prophecy is rather worryingly current in some Christian circles, even if most people don't have the nerve to be so very public in their predictions. Another manifestation is when a Christian says, 'God told me' – that they should take a particular job, move to a particular house, marry a particular person (lots of questions about that one). Or God told me that a certain course for the church was the right one, and that anyone who disagrees is therefore opposing him rather than disagreeing with me.

In a slightly different form – a bit more diffident and British, perhaps, but up there with the others – this might be, 'I felt the Lord was saying to me'.

Now, it's a bit unfair to equate a prediction of the fall of an Asian dictator with, say, the machinations at a Baptist church meeting. But they're points on the same spectrum, and they run the same risk of trivialising something that in Scripture was rare and vitally important.

When a prophet spoke, it didn't come out of nowhere. It was based on a deep knowledge of God's character and the consequences of wrongdoing. It was never random; it was about God's dealings with his people. And it was rare. The Old Testament spans a period of around 1,000 years, with many years when there's no record of prophecy at all. That sort of prophecy is rare in the New Testament as well; Agabus prophesies a famine 'across the entire Roman world' (Acts 11:28), but that acts as a spur to the disciples to provide relief for Christians in Judaea. And the crucial Council of Jerusalem in Acts 15, which established that the church would be Gentile as well as Jewish, said 'It seemed god to the Holy Spirit and to us' (verse 28); a clear statement of divine authority.

Does God speak today? Of course – audibly, sometimes, as Martin Saunders has written for Christian Today. I'm quite convinced he has spoken at least once to me.

But I really question that 'God told me' language. I don't doubt its sincerity, but I do doubt its appropriateness. I think some people are very prayerful and very attuned to God's character, and sometimes have a true sense of the right thing to do. I don't think that means God is speaking to them as he spoke to the prophets or to the church in Acts.

And I do think that sort of language can be used to stifle opposition, to manipulate, to get their own way.

To imagine that God speaks routinely risks trivialising revelation and devaluing the currency of prophecy. Not many readers will need much convincing that this is what Cindy Jacobs is doing, and it will be interesting to see what she says this time next year. But 'God told me' language is deeply rooted in some areas of the church. I wonder if we really know what we're claiming when we use it, and how close we are are to breaking one of the Ten Commandments: 'You shall not misuse the name of the Lord your God, for the Lord will not hold anyone guiltless who misuses his name' (Exodus 20:7).

Follow Mark Woods on Twitter: @RevMarkWoods