The National Alpha Initiative, which begins on 14 September, is co- ordinated by Holy Trinity Brompton (HTB), the richest and largest house of worship in the Church of England, and is personally endorsed by the Archbishop of Canterbury, Dr George Carey.
Billboards across the UK will invite non-believers to discover Jesus, while leaflets will be dropped through more than 1.5 million letterboxes. Themed posters are to appear on the notice boards of more than 4,000 churches, in a pounds 500,000 advertising blitz.
The unprecedented initiative will offer everyone in the country the chance to join a free 10-week "Alpha course". But the methods used on the course have been likened to mind-control, and Alpha has been accused of creating "a Mickey Mouse religion which is cheap, graceless and addictive".
The evangelical push, paid for by donations and a pounds 100 contribution from each of the churches involved, has been warmly welcomed by Dr Carey. In a message of support, he said: "As someone who has strongly supported the growth of Alpha (in) recent years, I was delighted to hear of the proposals for the National Alpha Initiative this September."
But Alpha is not the traditional face of Anglicanism. It presents its brand of Christianity in a carefully scripted package. Recruits are entertained over a three-course meal, and the after-dinner conversation in small pre- arranged groups centres on fundamental questions of existence and social problems. Weekend seminars follow, and the course finishes with a celebratory supper party.
Alpha's appeal is twofold: the music, dinner parties and weekends away offer its converts a cohesive social network, while the discussion groups provide answers to life's problems.
And those who embrace Alpha's teachings are expected to receive the holy spirit in a fit of wailing, shaking and falling on the floor. This demonstrative form of Christianity is known as "the Toronto blessing".
HTB takes pride in its use of "the method of welcome": free meals and friendship to people who "walk in off the street". But some see this approach as "love bombing" - the deliberate manipulation of visitors' emotions by displays of affection, a technique often used by religious cults.
In a recent interview, Donald Reeves, the former rector of St James's, Piccadilly, said the Church of England was moving away from being a national church. Nothing that HTB does, he said, can be described as Anglican. "They are moralistic, sex-obsessed and unkind - more like a cult than a church."
A cult, according to Ian Howarth, director of the Cult Information Centre in London, is a group or organisation which uses psychological coercion to recruit and indoctrinate people, so that all previous influences - spiritual, social, intellectual, financial - are replaced with a new set of values and explanations which change the recruit's "reality". Mr Howarth, himself an ex-cult member, said cult leaders - who are self- appointed and unaccountable - frequently employ mind control techniques similar to those adopted by Alpha.
Graham Baldwin, spokesman for Catalyst, an organisation which offers support to those who feel that religious zeal has been a negative influence on their lives, said: "People want the miraculous. We want to see the power of God. Everything needs to be a bit more dramatic than it used to be. How can you confirm that God is good? By seeing a miracle."
He finds the raw emotion of the Toronto Blessing difficult to handle. "A lot of people say it gives them a feeling of euphoria. I would put that down to adrenalin rather than the Holy Spirit. You could get the same feeling on the Last Night of the Proms. There is a problem in attributing these things to God."
However, Mr Howarth said he did not believe Alpha members were in any danger of being harmed by cult leaders. "The definition of a cult is only used when considering a group's method, and not its message or philosophy. Alpha is a Nineties way of sharing the Gospel. It is very, very popular."
Mr Howarth's colleague, Michelle Shirley, said the courses, which varied in the way they were delivered in individual churches, were run in a "very professional and organised way". But she admitted the centre had received complaints about Alpha. "The bulk of complaints have been made by Christians who are concerned about theological content." However, a small number were lodged by people who had attended the courses and had felt failures when they did not "receive something" in the Toronto Blessing. Miss Shirley urged would-be converts whose curiosity was aroused by Alpha's advertising campaign to be fully aware of what they were signing up for before joining.
Alpha was started 20 years ago by HTB's curate, Rev Charles Marnham. Rev Nicky Gumbel rewrote the Alpha doctrine in 1990, and in the following year, he ran four courses. In the first eight months of this year, 9,000 courses have been run in 58 countries, using Mr Gumbel's book, Questions of Life, as their basis. Alpha has been used by members of every denomination, from Roman Catholic to Lutheran.
Inquisitive non-churchgoers can tune into BBC1 on 20 September for a special Alpha edition of Songs of Praise.