Britain is under threat from a rising tide of "militant secularisation", a cabinet minister has warned.
Conservative co-chairwoman Baroness Warsi will say during an official visit to the Vatican that religion must be given a greater role in public life.
She warns in the Daily Telegraph that religion is being sidelined and will highlight the issue in a speech later.
Her visit marks the 30th anniversary of the re-establishment of full diplomatic ties between Britain and the Vatican.
The Tory peer will use her speech - the first to the Pontifical Ecclesiastical Academy by an outside minister - to call for Europe to become more "confident in its Christianity".
"In order to encourage social harmony, people need to feel stronger in their religious identities, more confident in their beliefs," she is due to say.
"In practice this means individuals not diluting their faiths and nations not denying their religious heritages.
"If you take this thought to its conclusion then the idea you're left with is this: Europe needs to become more confident in its Christianity."
Faith schoolsBaroness Warsi said examples of a "militant secularisation" taking hold of society included when signs of religion cannot be displayed or worn in government buildings, and when states will not fund faith schools.
Her comments come days after the High Court ruled that a Devon town council acted unlawfully by allowing prayers to be said at meetings.
And - as the BBC's religious affairs correspondent Robert Pigott reports - the Church of England could soon lose its traditional role as the provider of the chief chaplain to the Prison Service.
The Ministry of Justice has confirmed it is "considering arrangements" for appointing a new Chaplain-General - but the job might not go to an Anglican.
Our correspondent says the move may be seen by some Anglicans as the latest sign of the reduced influence of the "established" Church of England in public affairs.
The speech by Lady Warsi, Britain's first female Muslim Cabinet minister, will also compare the intolerance of religion with totalitarian regimes.
BBC political correspondent Louise Stewart said it was not the first time a senior Conservative had called for a revival of traditional Christian values.
"Last December, Prime Minister David Cameron said the UK was a Christian country and 'should not be afraid to say so'," she said.
Lady Warsi's two-day delegation of seven British ministers to the Holy See will include an audience with Pope Benedict XVI, who visited the UK in 2010.
Meanwhile, new research suggests Britons who declare themselves Christian display low levels of belief and practice.
Almost three quarters of the 1,136 people polled by Ipsos Mori agreed that religion should not influence public policy, and 92% agreed the law should apply to everyone equally, regardless of their personal beliefs.
It also found that 61% of Christians agreed homosexuals should have the same legal rights in all aspects of their lives as heterosexuals.
And a further 62% were in favour of a woman's right to have an abortion within the legal time limit.
The survey was conducted for the Richard Dawkins Foundation for Reason and Science (UK), which describes itself as promoting "scientific education, rationalism and humanism".
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