Our generosity as a nation to people in need should be based on our shared humanity, not our budget ups and downs, writes Tim Costello.

At 58, there's not much that shocks me. But the Coalition's plan to slash billions from our aid budget so the lucky country can build itself more roads has left me truly stunned and wondering what kind of nation we really want to live in.

Morally and strategically, this callous recalibration of our national priorities can only result in a diminished Australia.

Only 18 months ago, both major parties were strongly committed to increasing our aid budget to 0.5 per cent of gross national income (GNI) by 2015. This promise is now in tatters. It is heartbreaking to think of the millions of people all over the world whose lives could be worse off, or even lost, if this decision is implemented.

For five years, the Coalition has been promising to increase our aid budget to 0.5 per cent and now we discover they actually plan to reduce the current percentage.

To achieve their proposed cuts, it seems a Coalition government, if elected, will cull this year's aid budget to 0.33 per cent of GNI from the current level of 0.37. Even more astounding is that under the Coalition's plan, the aid budget will still have no chance by 2016 of reaching the level of funding originally committed for this year.

It's worth noting that the Coalition's announcement comes after a series of similar cutbacks by the Labor government that saw the projected aid budget lose $5.7 billion between 2012 and 2016. These continuing retreats go against the grain of both the Labor and Liberal traditions, and the impact of such a trend cannot be underestimated.

The gutting of the aid budget will not only be felt by people beyond our borders, but also by many here in Australia. A generation of youth idealism is being dismissed in one fell swoop.

And for those of us who dare to care about people beyond our borders, it is devastating to see both major parties abandoning our moral duty. As a prosperous nation, how can we justify redirecting money destined to help vulnerable people to build roads?

The tens of thousands of young Australians who have championed the poverty agenda for the past decade are the ones that understand best of all that in a world of increasing connectivity we can't afford to turn inward. Our aid program is key to our engagement with the rest of world, and in fact, reduction of poverty is directly linked to increased regional and global stability.

There is a sad irony that the Coalition plan is being floated just as Australia prepares to assume the presidency of the G20. This role comes with very real responsibilities and should compel us to reflect upon the type of leadership we have to offer the world. Yet just as we have secured this historic opportunity to lead the world's initiatives on global equality, we are allowing isolationism to distort our national values.

There is always the temptation for politicians facing an election to take refuge in the maxim that there are no votes in aid, but such a world view is outmoded and no longer relevant in our globalised world.

Our generosity as a nation to people in need should not be dependent on our economic circumstances but on our shared humanity.

I understand our country faces some economic challenges, but we should never, ever balance the books on the backs of the poor.

Tim Costello is chief executive of World Vision Australia. View his full profile here.