A leading Scottish churchman is accusing UK broadcasters of conducting a witch hunt against new Liberal Democrat leader Tim Farron, solely because of his Christian beliefs.

The Moderator of the Free Church of Scotland, Rev David Robertson, has been angered by the BBC and Channel 4’s treatment of the politician.

He said that BBC Radio Four’s John Humphreys “wouldn’t dare” probe Nick Clegg’s atheism and how it would affect his leadership of the party, in the way Mr Farron has faced repeated questioning on his faith.

Mr Robertson encouraged Christians across the UK to particularly pray for politicians in leadership positions who are bearing the brunt of an “intolerant, authoritarian and anti-Christian” society.

He said: “John Humphreys would never badger Nick Clegg about the impact his atheism would have on his decision making.

“Nor would Channel 4 repeatedly challenge the former Lib Dem leader’s personal moral views and the fact that he had boasted of having ‘no more than 30 notches’ on his bed.

“No reporter or news programme would ask questions based on such premises. Except when it comes to the crazy idea that a self-describing evangelical Christian could actually become a leader of a mainstream political party. Then all the gloves are off.”

The Free Church Moderator said that John Humphreys never asked other politicians about how their beliefs affect their decision-making.

“Why should it be considered disturbing that a Christian prays for wisdom and guidance to God? Is it not more disturbing that an atheist politician thinks that all wisdom lies within themselves, so they do not need any outside guidance? And what about asking about your views about sin?

“In the context of modern society it is of course the ultimate sin, the blasphemy against the Holy State, to even question whether any sexual activity, but especially homosexuality, can be considered sinful.”

He said the question was not asked to elicit information. “It was asked to accuse and mock.”

The Dundee minister concluded that these interviews demonstrated how intolerant, authoritarian and anti-Christian our society is becoming, at least at its elite levels.

“The danger is that Christian politicians and leaders will be pressured into compromise, and that the mockery narrative will be the background against which many ordinary Christians live their lives.We need the church to pray for those who are in authority, recognising them as the servants of God.

“We need Christian leaders who will be prophetic, proclaiming and living the Word of God in a culture that despises it.”