Tim Farron is warning Christianity is seen as 'dangerous' and 'offensive' after the former Liberal Democrat leader quit in July saying it was impossible to be an evangelical Christian and head of his party.

Warning of a 'threat to liberalism' Farron will say the UK is descending into 'groupthink, pack mentality and depressing conformity' in a lecture tonight.

'If you actively hold a faith that is more than an expression of cultural identity, a faith that forms the centre of your world view, you are deemed to be far worse than eccentric. You are dangerous. You are offensive,' he will say.

It comes after Farron faced repeated questioning about his faith during the 2017 general election campaign, particularly around whether he thought gay sex was a sin. He ducked the question on multiple occasions, saying his personal view didn't matter and pointing to his voting record which is largely in favour in increasingly gay rights.

But after intense pressure Farron eventually resigned as leader, issuing an extraordinary resignation statement saying: 'To be a political leader and to live as a committed Christian, to hold faithfully to the Bible's teaching, has felt impossible to me.'

In a lecture tonight for the religion think tank Theos, Farron will admit he handled those questions badly and 'demonstrated a lack of wisdom' but will argue 'liberalism will eat itself, is eating itself, may already have eaten itself'.

He will say: 'My experience is that although liberalism has won, it is now behaving like the established Church of the empire in the 4^th and 5^th centuries. It has gained ascendancy and lost itself in the process. It isn't very liberal any more.'

He will attack secularism saying it is 'staggeringly arrogant and obviously wrong' to think 'the absence of faith is the neutral position, and that the holding of a religious faith is eccentric'.

He will say: 'What appears now to be happening is that while the absence of faith is still thought to be the neutral position, holding a faith is only considered to be tolerably eccentric if it is merely cultural. But if your faith actually affects your world view in any way that puts it at odds with the mainstream, then your faith is considered to be malign and intolerable.'

He goes on: 'So there is no neutrality. Absence of faith is a valid world view, but it has no right to supremacy. If you believe it does have that right, then I respect your view, but you are not a liberal.'

Farron, who has been MP for Westmorland and Lonsdale since 2005, became a Christian at the age of 18.

His July statement prompted praise from Church leaders as well as warnings about the nature of his resignation. In it Farron said he was quitting the leadership after joining his party aged 16. 'It is in my blood, I love our history, our people, I thoroughly love my party.

'Imagine how proud I am to lead this party. And then imagine what would lead me to voluntarily relinquish that honour.

'In the words of Isaac Watts it would have to be something "so amazing, so divine, (it) demands my heart, my life, my all".'