Christianity is being squeezed out of the public sector in the UK, according to the Church of England's most senior lay official.

William Nye, who has been appointed as the Church's Secretary General after spending 20 years in senior Whitehall posts, told the Telegraph that a "secularising spirit" permeates the civil service, leading to an unspoken "squeezing out of Christianity" from national life.

He said that Christians working in the public sector rarely reveal their beliefs except to close friends and that faith is seen as "odd and unusual".

The CofE is planning to spend millions in an effort to arrest the national decline in churchgoing. Nye said he was optimistic attendance would recover but said decline was likely for the next five years.

He said he was glad to work somewhere he could speak openly about his faith.

"I think there has been, in the 20 years I was in the public sector, a sort of squeezing out of Christianity from many aspects of the public sector," he told the Telegraph.

"[It is] not universal – obviously there are chaplains in hospitals, there are chaplains in prisons – and I don't think it is minsters doing it deliberately."

He said he had been asked recently to suggest candidates from within the civil service for a senior post in the CofE.

"I had to say, 'You know I'm not sure I would be able to think of many people because, why would I know about anyone in government who is a Christian unless they are a personal friend?'

"Personal friends might have revealed to me that they are Christians but other people in government, central government departments, wouldn't do that.

"They wouldn't let it be known that they were Christians."

He added: "I think people who aren't in the public sector don't realise quite how that secularising spirit has led to the silencing of Christians in a way that isn't actually, I think, what people nationally want, or people are necessarily aware of.

"There is a lot of support, I think, for the Church of England doing its job as the Queen said 'gently and assuredly' – for the quiet work of the Church of England. But quiet work shouldn't mean silent."

He said it was "not really the 'done thing' to talk about religion in the 21st century, especially in government".

"You know: does it imply that you've somehow got some sort of axe to grind or it's something odd and unusual?"

Of his new appointment he said: "It is now a joy for me to be in a place where, although having spent 20 years not talking about my faith...one can talk more openly about it."