The Archbishop of Canterbury is among 79 religious leaders calling upon the G8 countries to fulfil their pledges on aid.
In a letter published in the Financial Times, they urge the heads of government to follow the UK in fulfilling existing commitments to spend 0.7% of national income on aid.
Other signatories include the Reverend Jonathan Edwards, General Secretary of the Baptist Union of Great Britain, the Reverend Roberta Rominger, General Secretary of the United Reformed Church, and the Reverend Dr Mark Wakelin, President of the Methodist Conference.
The letter reminds political leaders that there are only 1,000 days remaining before the 2015 deadline for the Millennium Development Goals (MDGs) to eradicate extreme global poverty.
"Meeting the remaining targets, while challenging, is possible – but only if governments do not waver from the moral and political commitments made over a decade ago," the letter stresses.
The letter highlights the need to tackle unfair tax practices and improve transparency so that developing countries do not lose out on the wealth they are creating.
This includes establishing a G8 Convention on Tax Transparency committing signatory countries to prevent individuals and companies from hiding wealth so that it is untraceable.
The religious leaders are hoping the UK presidency of the G8 will encourage greater action to address poverty, adding that the financial crisis is not an excuse to hold back.
"The number of people living in extreme poverty has been halved ahead of time and 14,000 fewer children die each day than in 1990. Yet one in eight people still go to bed hungry every night and more than 2 million die of malnutrition each year," they say.
"Reaching a purposeful consensus on these areas won't be easy. But, if the political will and moral leadership is forthcoming, this year's G8 could help to create an environment that encourages the conditions for inclusive, equitable and sustainable economic growth – conditions that are desperately needed if we are to realise the MDGs and even greater things beyond."
Signatories to the letter will be tweeting throughout the day with the hashtag #1000DaysToGo to help raise awareness of their call to G8 leaders and the responsibility to fulfil the MDGs.
The Right Reverend Nick Baines, Bishop of Bradford said: "With only 1000 days left to achieve the Millennium Development Goals set by the UN, it is imperative that the G8 Heads of Government set the pace and do not allow this to fail.
"I shall be tweeting my support using #1000DaysToGo and hoping the flood of comments encourages governments not to waver."