Lady Warsi is to warn of what she calls the "militant secularisation" of society and propose Christianity is given a central role in public life when she leads a high-level government delegation on an official visit to the pope.

In a speech on Tuesday she will say: "My fear is that, today, militant secularisation is taking hold of our societies. We see it in a number of things: when signs of religion cannot be displayed or worn in government buildings, and where religion is sidelined and downgraded in the public sphere.

"For me one of the most worrying aspects about this militant secularisation is that at its core and in its instincts it is deeply intolerant. It demonstrates similar traits to totalitarian regimes – denying people the right to a religious identity because they were frightened of the concept of multiple identities."

During the visit, held to celebrate the 30-year anniversary of the establishment of full diplomatic relations between the UK and the papacy, she will stress she is not calling for a theocracy but a more explicit role for religion in public life.

Some of the recent attempts by Christians to become involved in contemporary politics have been uneasy, including the near implosion of the administration of St Paul's Cathedral over the presence of the Occupy movement on its doorstep. There has also been sharp disagreements with the Church of England over secular issues such as bonuses and the role of banks.

Implicitly rejecting multiculturalism, Warsi, the first female Muslim to serve as a minister, will say that the best way to encourage social harmony is to put Christianity at the centre of public life.

She is taking six ministers to Rome, including Jeremy Hunt, the culture secretary, and Michael Moore, the Scottish secretary.

She will speak to the Pontifical Ecclesiastical Academy, the school for the next generation of papal diplomats, at which she will argue Europe needs to be more confident in its Christianity.

"Too often there is suspicion of faith in our continent hinging on a basic misconception – that to create equality and space for minorities we need to erase our religious heritage," she will say.

She will argue "people need to feel stronger in their religious identities, more confident in their beliefs". While individuals should not dilute their nations, nor should nations deny their religious heritages.

She will say that, "You cannot and should not extract these Christian foundations from the evolution of our nations any more than you should or could erase the spires from our landscapes".

She will deride the way in which across Europe and in the UK, "spirituality is suppressed divinity downgraded and where in the words of the Archbishop of Canterbury faith is looked down upon as the hobby of oddities, foreigners and minorities".

And she will say politicians "need to give faith a seat at the table in public life", saying "intolerant secularisation has to be held back by reaffirming the religious foundations on which our societies are built" .

The delegation is being lodged at the Vatican City State.