I have long enjoyed reading G K Chesterton's stories about the crime solving Roman Catholic priest Father Brown. I also enjoy watching the Father Brown programmes on television. However, whenever I watch the television programmes two things always strike me as odd.

The first is that in the programmes, unlike in Chesterton's original stories, the English Reformation appears never to have happened. In the village where Father Brown is the parish priest the medieval parish church (in reality the Anglican parish church of St Peter and St Paul, Blockley in Gloucestershire), which everyone in the village appears to attend, is still Roman Catholic rather than Church of England, and this is something which nobody seems to find the least bit surprising.

The second is what I have called the strange death of Father Brown. What I mean by this is that in the television programmes the Father Brown who appears in the original stories appears to have been killed off and replaced by someone who has the same name, but who is not the same person.

The reason I say this is because in the original stories Father Brown solves the crimes he comes across on the basis of an understanding of the world and of human nature stemming from Roman Catholic theology and pastoral experience. For example, in the very first Father Brown story, 'The Blue Cross,' Father Brown solves the case because of his keen awareness of human evil based on years of listening to people's sins in the confessional, and because he knows that the villain Flambeau is not really a priest since he has contravened Catholic theology by attacking reason whereas, says Father Brown, 'the Church affirms that God himself is bound by reason.'

Furthermore, in the original stories Father Brown also comments on what has taken place from a Roman Catholic theological perspective. Thus, in the story 'The Chief Mourner of Marne' a character declares that the crime that has been uncovered by Father Brown is unpardonable, and Father Brown then responds that as a Catholic priest he is under an inescapable obligation to pardon it:

''We have to touch such men, not with a bargepole, but with a benediction," he said. ''We have to say the word that will save them from hell. We alone are left to deliver them from despair when your human charity deserts them. Go on your own primrose path pardoning all your favourite vices and being generous to your fashionable crimes; and leave us in the darkness, vampires of the night, to console those who really need consolation; who do things really indefensible, things that neither the world nor they themselves can defend; and none but a priest will pardon. Leave us with the men who commit the mean and revolting and real crimes; mean as St. Peter when the cock crew, and yet the dawn came.''

In short, in the original stories, the Roman Catholic version of the Christian faith held by Father Brown is front and centre. However, in the television programmes it is not. In these programmes it is not his Catholic faith that enables Father Brown to solve crime, nor does he give a Catholic commentary on what occurs. Father Brown is still a Catholic priest, but that is incidental rather than central to what takes place. He is a man without the same motivation, and he consequently does not behave in the same way.

Both the elements that make the Father Brown television programmes different from the original Father Brown stories are important because they point us to the truth that we now have a mainstream media that for the most part reflects a secular worldview which neither understands Christianity, nor takes it seriously. Anyone who had even a basic understanding of the history of Christianity in this country would not have a local Roman Catholic congregation worshipping in a medieval parish church, and anyone who took Catholic Christianity seriously would give it the same place in the Father Brown television stories that it occupies in Chesterton's original stories.

The importance of diversity is a big mantra for the mainstream media these days. We are constantly told how good it is that the media is now much more diverse than it used to be, but that yet more diversity is required. However, if you investigate what this diversity includes you will find that it is in fact a strictly limited diversity. It is a diversity that, with the exception of niche programmes such as Songs of Praise, almost never includes giving space for the exploration and expression of traditional Christian theology and practice, whether in a Catholic, Protestant, or Orthodox form.

For example, drama series do not depict it as normal for people to have a living faith in Jesus Christ as the mainspring of their lives. When was the last time you saw, or heard, a character in a television or radio drama given space to explain why they believe in Jesus' resurrection and why it is so important for them?

For another example, there are numerous documentaries from people like Brian Cox setting out a secular view of the universe. Where are the documentaries from Christian scientists like John Lennox or Alister McGrath explaining the universe from a Christian perspective?

For a third example, there are now numerous programmes looking sympathetically at every conceivable form of human sexual identity and behaviour. Where are the programmes giving believers the space to make out the case for accepting a traditional Christian view of human identity and sexual conduct?

What should Christian believers do in the face of this situation? Two things. First, they should consistently and insistently raise the question of whether the mainstream media really believes in diversity, and, if so, why does this not include space for orthodox Christianity. Secondly, they need to be adventurous in finding alternative ways of getting orthodox Christian theology out into the public square, bypassing the mainstream media blockade.

Martin Davie is a lay Anglican theologian and Associate Tutor in Doctrine at Wycliffe Hall, Oxford.