Gordon Brown hailed a march of hundreds of the world's religious leaders, calling for urgent action to tackle global poverty, today, as "the greatest public demonstration of faith" Britain has ever seen.
Most of the 670 Anglican bishops attending the Lambeth Conference, led by the Archbishop of Canterbury, Dr Rowan Williams, moved slowly and silently behind a banner telling governments to Keep the Promise Halve Poverty by 2015, past Downing Street and the Houses of Parliament to Lambeth Palace.
The Prime Minister told the bishops, who had been joined by up to 1,500 faith leaders, diplomats, politicians and heads of charity, on the march, that "100 years is too long to wait for justice and that is why we must act now".
Mr Brown joined Dr Williams in warning that time was running out if the Millennium Development Goals (MBGs), set in 2000 to halve poverty by 2015, were to be achieved.
Mr Brown told the bishops at a rally in the courtyard of Lambeth Palace: "This is one of the greatest public demonstrations of faith that this country has ever seen.
"You have sent a symbol, a very clear message with rising force that poverty can be eradicated, poverty must be eradicated and if we all work together for change poverty will be eradicated."
The aim of today's march, despite potential splits in the community over gay or women priests, was to unite in what was dubbed as a "walk of witness and solidarity" as a powerful voice against poverty.
Mr Brown said: "If every child is precious - as they are, and from my own experience know that every child is unique and special - then they deserve the best in life."
He urged the bishops on the Lambeth walk to go back and demand their government to hit targets so that every child is in schooling by 2015 and to invest in training of doctors, nurses and midwives so that 10 million children no longer die "unnecessarily" of avoidable diseases such as malaria.
With political will power plus technological developments and new medicines, the world should also be able to try and tackle the Aids crisis, he said.
And to help the 100 million people suffering from famine, the bishops should also demand 20 million dollars for food aid and a review of agricultural protectionism to help people grow food for themselves as part of a "green revolution for Africa", Mr Brown suggested.
Despite the daunting task the world has a chance to eradicate poverty and they are losing the chance to do so.
The bishops were told there is room for hope and were reminded of how little people and the oppressed joining forces to tackle injustices have changed the world.
Mr Brown said: "Twenty years ago they said it was an impossible dream that apartheid would end, an impossible dream that Nelson Mandela would be free, that the Cold War would be over and the Berlin Wall would come down, but it is men and women of faith who came together and fought hard for this change and change happened."
In what he hopes will be a wake-up call to the world, Dr Williams told those gathered that the Church is a powerful voice at this crucial time.
He said: "As the world grows smaller the truth is that the need for anyone in our community is sooner or later going to be the need of anyone in our global community.
"This is not and should not be a surprise for those of us to hold the Christian faith who believe that when one part of the body suffers it all suffers."
Cardinal Cormac Murphy O'Connor, the Roman Catholic archbishop of Westminster and the leader of the Evangelical Alliance the Rev Joel Edwards were among the walkers.
Chief Rabbi Sir Jonathan Sacks and the former Secretary General of the Muslim Council of Britain Sir Iqbal Sacranie also took to the streets today.
Reverend Daniel Deng Bul, the archbishop of Sudan, said: "This walk is to remind the government and all the people to say that enough is enough and justice has to be done around the world.
"This is us saying we are for it. I know that in my own country it is a very serious situation because many people are coming back from displaced camps and refuge camps to a country where there are no services.
"You can see a lot of diseases. There are a lot of water-borne diseases like malaria, and there also Aids.
"Many people do not have one meal a day and they do not get education. They are human beings and it should not be happening in the world."