In many developing countries religion is one of the most powerful sources of personal identity – for good and ill. Understanding these identities is critical to tackling conflict and understanding politics. Equally, the role of religion in forming attitudes and behaviour can be profoundly important in addressing the causes and effects of poverty.

In countries where the state has a weak or erratic presence, people often organise essential services through faith communities: the churches are the largest healthcare providers in sub-Saharan Africa. Faith can also be a channel through which people become engaged as active citizens, and press for change, whether in recent Kenyan elections or the protests in Burma.

A couple of weeks ago I spoke in Rimini, northern Italy. Twenty thousand people of faith attended the conference to discuss and examine their Catholicism. All over the world, week in week out, billions more people of different faiths take time to practise their religious beliefs. Faith remains a major force and source of immense influence around the world.

At the turn of the millennium government understood that the churches could deliver powerful and effective advocacy messages in favour of development objectives: on aid, trade and debt. With Gordon Brown and myself, they were mainly knocking on an open door. We valued that commitment to making poverty history. The great London multi-faith march by religious leaders this year to promote the Millennium Development Goals was further evidence of the power wielded by faith communities when they work together.

We know they are effective advocates – that's not the key question in development. But do religious leaders and faith communities in the developing world have the capacity to contribute effectively to national development plans? Or are they only interested in the welfare of their own constituencies, so that funding them would be divisive?

The answer is providing help to enable faith communities to develop their capabilities. It doesn't make sense for them to do this separately. This is a core part of the vision of my Faith Foundation.When faith communities collaborate for justice and human development there is a double payoff: things get done and respect and understanding between them grows.

In Mozambique there are excellent programmes training leaders from different faiths together so that they can play their role in health education among their communities. Faith communities given training, some funding and mobile phones, could provide governments with missing data about incidence of disease and the effectiveness of healthcare delivery in parts of their populations where government has negligible access. But there is little research on what these communities need, even what they are already doing, to know what interventions are required. Dfid is funding one of the first research consortiums studying faith and development based at Birmingham University. But we need more.

Religions know a lot about wellbeing. But a small minority are part of the problem. They do not start off with a belief in a merciful and compassionate God and reflect this in work for integral human development, peace and justice. As Pope Benedict points out in his recent encyclical, there are religious ideologies that completely deny the very value of development. But it would be wrong to pump up instances of the wilful perversion of religion into a blanket condemnation of faith.

Let's be clear. Faith communities are not NGOs in the normal sense. They were not consciously created for service delivery, health care, advocacy, or education. They are a gathered people brought together by often ancient religious traditions carried through the generations by a community of faith. They are centred on worship, usually rooted in sacred texts and have a particular spirituality and set of symbols.They are involved in healthcare and education because of their particular spirituality and what they believe are the simple demands of justice. Their obligation is to God or their founding teacher. They bring to it a common concern for the human dignity of the person that embraces the spiritual.

Faith has traditionally been a blind spot in the UK policy arena, which has tended to be dominated by economic and political discourses.

The Observer journalist Anthony Sampson told a story from his time as ghost writer for the 1980 Brandt Report. It was at the time a major contribution to the analysis of the problems of international development. After it was published, Sampson asked Willy Brandt how he felt about it. "Too many economists, not enough anthropologists" was his somewhat cryptic reply. He meant, of course, that the report had not paid enough attention to the importance of culture and religion in determining outcomes in development. Now he had his faults, but excessive religiosity was not one of them. The developing world was steeped in religious ideas and practice. You neglected them at the cost of effective development. At the time the secular world of econometrics and development experts, on the whole, simply didn't get it. He had spotted the problem. The role of faith in development is complex and not well enough understood. The seminar series we're running with Dfid, Islamic Relief, World Vision and Oxfam is designed to be an open, and if necessary, critical discussion about the role that faith can play in development.

It's timely. Government is taking an increasing interest in faith and development, and the faith community increasingly has a viable role alongside major development organisations in working to achieve the MDGs.

We live in a global community. The contest for scarce resources, water and oil, will be intense by mid-century. Our interdependence is manifest whether at the level of climate change or global financial markets. The daunting task of bringing 1.4 billion people out of dire poverty, feeding the 900 million who go to bed hungry every day, faces religious communities and secular humanists alike. We need the inter-religious and inter-cultural dialogue that turns neighbours into friends able to work together to confront the threats to our common security.

This speech will be delivered as the first in a series of seminars exploring faith and development hosted by The Tony Blair Faith Foundation, the Department for International Development, Islamic Relief, World Vision and Oxfam and debated on Comment is free: belief. A selection of on-topic comments will be put forward as questions at the end of the live session on Monday evening