To many, the rally is a sign of hope; to some, including some women's groups, it has a sinister side. Mary Dejevsky explains.
Today's mass gathering in the Washington Mall, the broad thoroughfare more used to carnival parades and protests than prayer meetings, is called "Stand in the Gap", a phrase taken from the Old Testament prophet Ezekiel who "looked for a man among them who would build up the wall and stand before me in the gap on behalf of the land, so I would not have to destroy it". Ezekiel "found none".
The organisers, hoping to succeed where the prophet failed, are Promise Keepers, a seven-year old organisation led by a football coach turned evangelist, Bill McCartney, that has grown from a core of fewer than 100 who attended the first rally in Denver seven years ago to a nationwide organisation with more than one million members last year and an income of almost US$100m (pounds 62m).
Although its founder, Bill McCartney, like the majority of members, is white, membership is open to all men, of whatever age and ethnic group, who are prepared to sign up to seven promises, which include "honouring Jesus Christ through worship, prayer and obedience to God's word", "building strong marriages and families through love, protection and biblical values" and a commitment to church attendance and participation.
Its supporters, of whom there are very many across a broad political and social spectrum, place the movement in a benign American tradition of male Christian movements, from the muscular Christianity of the early years of this century, through the Boy Scout movement.
They note approvingly that it lacks the racial element of Louis Farrakhan's exclusively black Million Man March of two years ago - with which today's rally is sometimes compared. So, thousands of men are committing themselves to Christian and family values; what is so wrong with that?
Two things, according to its critics. One, especially for its female critics, is its male exclusiveness and emphasis on male authority. If it is so serious about family values, they say, why is it that women are kept out? And - a concern, voiced strongly by Patricia Ireland, leader of the National Organisation of Women - why the emphasis on female submission and obedience within the family? The Promise Keepers movement is seen by Ms Ireland and others as an attempt by men to take back the ground that women have gained thanks to the women's movement, put women back in the kitchen and make them subservient to their husbands. Bill McCartney defends the movement's maleness by arguing that because men are at the root of so much that has failed in society, it makes sense to call them to account. Some female supporters of Promise Keepers say that the sense of responsibility and involvement in the family that men acquire when they join the organisation simply makes them better husbands and fathers and - despite the teaching that the husband is head of the household - does nothing to restrict the wife's freedom.
The other criticism is that Promise Keepers has a right-wing conservative agenda and is intended to be the fifth column of the religious right and the Republican Party for the next presidential election, taking over where the declining Christian Coalition left off. Mr McCartney denies any political agenda, and says his anti-abortion views are personal and not imposed on the movement.
In any case, Promise Keepers may just have peaked too soon to have a major political impact. Income and attendance at rallies this year has fallen by one third - a decline that today's rally will arrest.
By yesterday morning, armies of professionals and volunteers were erecting huge screens and a giant platform on the Mall. Sandwich and soft-drinks vendors were establishing their pitches and more than 1,000 portable toilets were being wheeled into place. The only question was: how many would turn up?