In a highly significant move, ministers will fight a case at the European Court of Human Rights in which two British women will seek to establish their right to display the cross.
It is the first time that the Government has been forced to state whether it backs the right of Christians to wear the symbol at work.
A document seen by The Sunday Telegraph discloses that ministers will argue that because it is not a "requirement" of the Christian faith, employers can ban the wearing of the cross and sack workers who insist on doing so.
The Government’s position received an angry response last night from prominent figures including Lord Carey, the former Archbishop of Canterbury.
He accused ministers and the courts of "dictating" to Christians and said it was another example of Christianity becoming sidelined in official life.
The Strasbourg case hinges on whether human rights laws protect the right to wear a cross or crucifix at work under Article 9 of the European Convention on Human Rights.
It states: "Everyone has the right to freedom of thought, conscience and religion; this right includes freedom to change his religion or belief, and freedom, either alone or in community with others and in public or private, to manifest his religion or belief, in worship, teaching, practice and observance."
The Christian women bringing the case, Nadia Eweida and Shirley Chaplin, claim that they were discriminated against when their employers barred them from wearing the symbols.
They want the European Court to rule that this breached their human right to manifest their religion.
The Government’s official response states that wearing the cross is not a "requirement of the faith" and therefore does not fall under the remit of Article 9.
Lawyers for the two women claim that the Government is setting the bar too high and that "manifesting" religion includes doing things that are not a "requirement of the faith", and that they are therefore protected by human rights.
They say that Christians are given less protection than members of other religions who have been granted special status for garments or symbols such as the Sikh turban and kara bracelet, or the Muslim hijab.
Last year it emerged that Mrs Eweida, a British Airways worker, and Mrs Chaplin, a nurse, had taken their fight to the European Court in Strasbourg after both faced disciplinary action for wearing a cross at work.
Mrs Eweida’s case dates from 2006 when she was suspended for refusing to take off the cross which her employers claimed breached BA’s uniform code.
The 61 year-old, from Twickenham, is a Coptic Christian who argued that BA allowed members of other faiths to wear religious garments and symbols.
BA later changed its uniform policy but Mrs Eweida lost her challenge against an earlier employment tribunal decision at the Court of Appeal and in May 2010 was refused permission to go to the Supreme Court.
Mrs Chaplin, 56, from Exeter, was barred from working on wards by Royal Devon and Exeter NHS Trust after she refused to hide the cross she wore on a necklace chain, ending 31 years of nursing.
The Government claims the two women’s application to the Strasbourg court is "manifestly ill-founded".
Its response states: "The Government submit that… the applicants’ wearing of a visible cross or crucifix was not a manifestation of their religion or belief within the meaning of Article 9, and…the restriction on the applicants' wearing of a visible cross or crucifix was not an ‘interference’ with their rights protected by Article 9."
The response, prepared by the Foreign Office, adds: "In neither case is there any suggestion that the wearing of a visible cross or crucifix was a generally recognised form of practising the Christian faith, still less one that is regarded (including by the applicants themselves) as a requirement of the faith."
Christian groups described the Government’s stance as "extraordinary".
Lord Carey said: "The reasoning is based on a wholly inappropriate judgment of matters of theology and worship about which they can claim no expertise.
"The irony is that when governments and courts dictate to Christians that the cross is a matter of insignificance, it becomes an even more important symbol and expression of our faith."
The Strasbourg cases brought by Mrs Chaplin and Mr McFarlane are supported by the Christian Legal Centre which has instructed Paul Diamond, a leading human rights barrister.
Judges in Strasbourg will next decide whether all four cases will progress to full hearings.
If they proceed, the cases will test how religious rights are balanced against equality laws designed to prohibit discrimination.
Andrea Williams, the director of the Christian Legal Centre, said: "It is extraordinary that a Conservative government should argue that the wearing of a cross is not a generally recognised practice of the Christian faith.
"What next? Will our courts overrule the Ten Commandments?"
Growing anger among Christians will be highlighted today by Delia Smith, the television chef and practising Roman Catholic, who will issue a Lent appeal on behalf the Church’s charity, Cafod, accusing "militant neo-atheists and devout secularists" of "busting a gut to drive us off the radar and try to convince us that we hardly exist".
I don't often find myself keeping company with the rather silly, inconsequential and hard-of-thinking Lord George Leonard Carey, Baron Carey of Clifton PC, FRSA, FKC that is, a former Archbishop of Canterbury and one of natures more boring, intolerant, confused, pompous and bombastic former prelates, but on this occassion I am, surprisingly, on the same side. I wait with bated breath, however, for the bishop to put his foot in it, as he usually does, and weaken our entire case in the process.
However, it is deeply shaming that this dispute cannot be sorted out in our own courts but has to be appealed to the barely literate, undereducated and very sub-standard judges at the ECtHR in Strasbourg. Common sense might prevail, but don't hold your breath.
As for being badly let down by the Conservative Party I find that in this day and age that is only to be expected - just like most modern conservative politicians they are too cowardly to do anything wrong and too pusillanimous to do anything right with the end result that it doesn't matter who is in power because we will still get sold down the river no matter what.