More than 3,000 people took part in an ecumenical service at Methodist Central Hall in Westminster on Saturday to put pressure on G8 leaders to address the causes of global hunger.
The head of the Roman Catholic Church in England and Wales, Vincent Nichols, said in an address that the hunger experienced by millions of people around the world every day was a "responsibility we all must share".
"These are our brothers and sisters and their suffering is also ours. There can be no excuse that in a world of plenty, so many go without," he said.
"We have gathered today to show our solidarity with those millions who are made to have less because the food system is skewed in favour of those with both financial and political power."
He urged G8 leaders meeting in Northern Ireland over the coming days to tackle issues like financial transparency, tax evasion, land and resource grabbing by large corporations, and the honouring of aid pledges.
He stressed that these objectives were "achievable" if governments and people were willing to change and pay the cost necessary for others to access the things they need for a dignified life.
"It must begin with me," he added.
In a video message to the congregation, the Archbishop of Canterbury, the Most Reverend Justin Welby, said it was his prayer that Britain would be "deeply committed to enabling people to be self-sustaining so that global hunger can be ended in our lifetimes".
"The G8 is the centre of financial resource and power, in all kinds of ways," he said.
"Many members of the G8 are increasingly deeply committed to using that power for the global good, and our own government is one that has very courageously, at a time of austerity, increased its giving in aid.
"But it's important that we put before them the needs of the global community in which we live, with which we are interdependent."
General Secretary of the Methodist Church, Dr Martyn Atkins, spoke of his hope that the church would change the world by speaking with one voice.
"We expect and demand action on hunger at the forthcoming G8 summit ... How right and proper we are doing that together as Christians," he said.
The congregation heard about the reality of hunger from Aimee Manimani, of World Vision Democratic Republic of Congo.
She told how malnutrition is killing more children than the conflict blighting the country. Although the DRC is mineral rich, she said most of the revenue was not benefitting the people because it was being sold to other countries tax free.
"Instead of helping people to improve their life, the country is getting worse and worse," she said.
The service was held before thousands gathered for a giant rally in Hyde Park pushing for action by the G8 leaders.
The Big IF rally was joined by Microsoft founder Bill Gates and the former Archbishop of Canterbury Rowan Williams, who led a minute's silence for the two million children who die from hunger each year.
The service and rally were held to coincide with David Cameron's hunger summit where the UK pledged to give an extra £375m to help feed children at risk of malnutrition.