Driving to preach at last Sunday's service at the St Kilda Baptist Church, of which he is a former minister, he told me that 25 years ago, 60,000 of the world's children aged less than five were dying each day. Today it has fallen to 20,000.

That is good news for those who survive but, he says, there is so much more which must be done.

The question I raise is how I and most other well-off people would cope if confronted, as Costello is, when visiting the world's most impoverished people.

He says there is a paradox.

''I simply can't imagine how I or my family, or any Australian, would survive without utter psychological collapse given that hardship. But I find in these places extraordinary joy, community and celebration.''

Then he returns to Australia to find an epidemic of depression, a high rate of youth suicide, drug use and community fragmentation.

Despite this country's affluence, he says Australians have never appeared as grumpy or disillusioned. For this he blames in part a toxic federal Parliament, hamstrung in responding to the big issues of our day.

In his new book, Hope: Moments of inspiration in a challenging world, Costello reflects on the importance of faith, hope and love.

''You can see we have been making progress in some of the areas I care about. But at the moment I think the world is gripped by fear rather than hope.''

He says the decline in the death rate of young children is attributable to a focus on the millennium goals. This includes a focus not only on aid but on the quality of aid. Holding up the global score card to world attention has been a major achievement.

World Vision is a Christian relief, development and advocacy organisation dedicated to working with children, families and communities to overcome poverty. It offers Australians the opportunity to sponsor a child in need at $43 a month. Costello says this is a good start for those wanting to help.

He says many parents tell him it was their children who encouraged child sponsorship. Having done so, it has helped the children to be more grateful for what they have.

Yet in the name of a budget surplus, Australia's government reneged on its commitment to increase overseas aid from 3.5 per cent to 3.8 per cent of national income. Costello says this will cost about 200,000 lives this year.

Yet he is not asking well-off Australians to give up certain luxuries.

''We can still enjoy our lifestyle, carbon footprint aside, and fulfil our requirements to deal with poverty according to the millennium development goals.''