In his office behind a cluster of high-rise flats at the eastern edge of Glasgow, Tony Sargent is sorting through paperwork as Pachelbel's Canon plays quietly in the background. The room is filled with framed photographs that give clues to the different strands of Tony's life and work, but one picture in particular, of a little girl in India, is especially important to him.

"This lass here," says Tony, holding the frame up, "I look at every day. It makes me quite emotional. I met her 20 years ago in a Calcutta slum. I don't know her name. She was walking in front of me, talking in her own language. I didn't understand what she was saying, but I had an Indian guy alongside me and I asked him.

"The girl had a black sack on her back and she kept stooping to pick up bits and pieces of rags. I was told that she was saying, I don't want to be a rag-picker all my life.' It sounds like a very self-serving story, but I had her tracked to where she lived."

Since their chance encounter, Tony has been anonymously sponsoring the girl through school and college. "You can't change the world, but you can change somebody's world and it costs very little. All she knows is that somewhere, once in her life, somebody overheard what she was saying. I can't tell you the kick I get out of that."

The ability to change one life is something to which Tony keeps coming back, but in reality he has changed the lives of many, a fact recently recognised when he was given an honorary doctorate by Strathclyde University. His work in India alone includes setting up an old people's home after stumbling across a group of elderly people living in a cattle shed, establishing a new hospital in Mumbai (with a second to be completed next year) and, most recently, opening a drop-in centre for 400 street kids in Calcutta.

Perhaps unsurprisingly, given that he has visited India 45 times in the past 20 years, Tony crossed paths with Mother Teresa. When her name is first mentioned, he reaches over and picks up a photo from his desk which shows them talking with each other.

He met her through his work with Emmanuel Ministries, an organisation based in Calcutta. "I was with Mother Teresa just before she died. One of the things she challenged me to do was to ensure that, in our preaching ministry, we also had a ministry for the poor.

"I found her to be a very gentle lady. She told me she had been speaking with Diana the Princess of Wales and was keen for her to do more work there."

Before coming to Glasgow to set up the International Christian College, where he is principal, Tony was a pastor for 28 years at a church in Worthing, Sussex, which was heavily involved in international work. He brought that outlook with him to Glasgow. The college gets no public money and relies on student fees and gifts for its funding. The majority of students are from the UK, but many come from abroad to study as ministers, missionaries and youth workers. When they return home to set up projects, they often call on Tony for assistance.

One alumnus, Gabriel Kijambu, is now heading up a project to transform part of the former "killing fields" of Idi Amin in Uganda into a children's village. The project hopes to transform a 22-acre area in Luwero, about 10 miles outside Kampala, into a refuge for 400 orphans. The area was the scene of horrific ethnic cleansing that left many children without parents.

"Gabriel was born into a poor family, and he used his initiative to set up a charity, independent of the college," explains Tony. "A vision was born of bringing kids together in a village community."

The land, which was bought three years ago, has been cultivated and is already home to 50 orphans. In addition to their accommodation, the village will have a school and staff quarters. "Instead of having just one big house for the orphans, we hope to have about two or three units to make it feel less institutional. We're also trying to make it self-supporting," says Tony.

"This guy, he had no backing apart from us. But I have a ministry of making rich people feel uncomfortable, so I don't mind begging for money."

Despite his laughter when he says this, Tony could not be more serious. "If you earn £30,000 a year, you are in the top 10% of the world's earning bracket. If you have an asset of more than £250,000, which a lot of people in Scotland have because of the price of their houses, you're in the top 1%. The net result of this is that in some Glasgow suburbs, they haven't got a clue about how the rest of the world is living. Yet we can do such a lot without necessarily becoming poverty-stricken ourselves.

"One of the most fulfilling experiences in life, emotionally, is to know that you've helped change. This isn't being goody-goody or pie in the sky. God knows, if you were living in that kind of village, you would be so grateful."

Although much of his work is with organisations in the Third World, Tony is also involved in local projects, including the Buddies Bus, which offers coffee and warmth to party-goers on Sauchiehall Street in Glasgow. "One of the most amazing things is how the folks who pass by, far from laughing at and scorning us, show appreciation by giving us hugs and sweets," says Tony.

While the volunteers on the bus are happy to give spiritual advice to those who ask for it, Tony says their main aim is to keep people safe. He acknowledges that it is a good way for the church to help address some of the most pressing social issues in a practical way. He believes the church is, to an extent, preoccupied with the wrong issues: "The world has squeezed the church, to some degree, into its own mould. The recent Church of England conference in York discussed women bishops, but how many hundreds of kids are starving every day in Iraq?

"If you put together all that the Americans and the British have spent in Iraq, we could have fed the world's poor for 10 years. I think what the world is expecting is the church to say something, and sometimes we are just fiddling around with the wrong things. There are billions of women in the world today who walk four miles to get a pail of water, and kids who can't wash and aren't fed properly. What the world is asking the church to do is to demonstrate, through its work as well as through the word, its convictions."

He admits that the suffering he has witnessed around the world has pushed his beliefs to their limits. "I have problems because God sometimes looks to be so inactive. It's hard to see something and relate that to an infinite, compassionate God. So there is an area where my beliefs stray towards agnosticism - but not that it makes me question the being, because I believe ultimately there is an answer. I do believe that God identifies with human suffering. Because I believe in eternal life, I believe there is a scale of balances that can be levelled."

His beliefs were also tested when tragedy visited his own family. His much-loved father endured a long, painful death after becoming physically dependent on the drugs he was administered during an operation. "My dad was a good man and he died a horrible death, which he didn't deserve. The most difficult thing I did in life was to preach to hundreds of people the following Sunday. I don't have all the answers, but I do believe there is more evidence as to the benevolence and the existence of God than there is to the contrary, and that itself gives me faith."