Yet until David Alton, the Liberal Democrat MP and the MCD's best-known spokesman, announced last week that he was leaving Parliament, the body he co-founded had seldom been heard of outside church confines.
Mr Alton, the semi-detached member of Paddy Ashdown's parliamentary party, foresees the day when a fully-fledged Christian Democrat Party, on European lines, might emerge from the movement he helped set up only five years ago.
If politically-minded Christians fail to convert the major parties to their objectives, he argues, "those who wished to do so could proceed with the development of a party and agenda unashamedly based on Judaeo- Christian values. As in the rest of Europe, its appeal would go way beyond the church-going or even nominally believing community". Christians should not close off this option, he insists. "A cosy circle organising genteel parties or London dinners will never be listened to."
But that was how it all started. In January 1989, Mr Alton brought together 20 like-minded souls for a three-day think-in at Prinknash Abbey in Gloucestershire. They agreed on five uniting values: respect for life, social justice, reconciliation, active compassion and good stewardship. They called themselves the Epiphany Group, and held a number of dinners at the Commons before setting up a political movement under the chairmanship of Dr Robert Song of Cranmer College, Durham. The new body had its inaugural conference in November 1990.
The MCD has since gone from strength to strength, attracting "political animals who are not at home in any existing party". It has forged links with Christian Democrats on the continent - it is enthusiastically, even federally European - and it has drawn up policy statements on full employment and the evils of debt. In October, it has its annual conference in Birmingham, where speakers include Tory peer Baroness Cox.
But a casual reader of the bi-monthly Christian Democrat (circulation 45,000, mainly through churches) might be forgiven for thinking the movement has been captured by the radical religious right. Its agenda is unrelentingly "pro-life": anti-abortion, hostile to China's population-control programme, and opposed to "Emily's List" of women aspiring to be Labour MPs, who have to be "pro-choice".
Virtually the whole of the front page of the current edition is taken up by an emotive advertisement for the Society for the Protection of Unborn Children, and a lead story headlined "Abortion agonies", which discloses details of the movement's campaign "to highlight foetal pain and terror", and to change the abortion laws. Inside is a page devoted to establishing a link between abortion and breast cancer. There is also a proposal to set up "Esther's List", which would have a "pro-life" agenda.
Mr Alton rejects the "single-issue" tag, pointing to the variety of topics on which the movement has issued policy papers. He also stresses the organisation's all-party support, though this may be more apparent than real. It has some Labour members, but the late John Smith instructed Labour MPs to sever their links with the movement because of its relationship with continental Christian Democrats and the European People's Party, which is in opposition to the dominant Socialist group at Strasbourg.
Nor is there much Christian love lost between the MCD and the Christian Socialist Movement, of which Tony Blair is a strong supporter. Chris Bryant, chair of the 2,300-member CSM, says Mr Alton's organisation is composed of "people who are theologically conservative". He adds: "MCD is an organisation that pretends to bring together people from all political parties around core Christian themes but, I fear, generally attracts conservative-thinking people around a personal moral agenda rather than a political one.
"A Christian Democrat party would be a nonsense - and close to heretical, because it enlists Jesus or God to a political cause." And a Christian Democrat government, he says, would turn Britain into a theocracy. "You would outlaw abortion, divorce and homosexuality because the state would need to legislate on personal moral issues."
Mr Alton, who is likely to take a professorial chair of Politics and Citizenship at Liverpool John Moores University after the general election, admits that a Christian Democrat party could get off the ground only if the electoral system were changed. "It would be absurd to contest elections under the first-past-the-post system. You would strike the rocks very rapidly. No doubt if you change the voting system it would be very surprising if there was not a fundamental realignment of politics."