He has been shouted at, kicked, punched, spat at and even had a bucket of water thrown over him in the pursuit of his "calling" to preach to shoppers.

But none of that puts off Pastor Francis Oviawe. Today like any other in the last seven years, he is to be found standing proudly in the middle of the Podium – the plaza at the centre of Bristol's Broadmead – Bible in hand, preaching at the top of his voice.

As ever, you hear the 66-year-old long before he comes into view behind the streaming crowds of oblivious shoppers. He receives abuse on a daily basis. More often, he is simply ignored by passing shoppers. Very occasionally, he makes a convert from the crowd.

"It's easy to stand firm against those who are abusing you when God is on your side," he tells me, as we walk away from the Podium towards the nearest coffee shop.

When he stops shouting about "repentance" and "love" and "the great and terrible day of judgement", the Nigerian-born preacher is remarkably softly spoken. His fire-and-brimstone frown breaks easily into a warm smile from the moment he steps away from his stage.

"I didn't always find it easy," he confides. "When I first started the street preaching back in 2005, I was terrified. Standing there, clutching my Bible, taking a deep breath and shouting above the crowd for the first time was horrendous.

"But I'd had a dream in which I was preaching in the street. There was a lion striding down the middle of Broadmead in my dream. I knew what that meant – God was telling me to be brave."

But courage is not something Francis has ever been short of – not when he left behind his childhood home in Africa in search of a British university education at the age of 22, only to find casual racism at every turn in 1960s Britain.

Nor when he gave up his degree course – and abandoned his dream of becoming a doctor – after being "told" to do so by "the voice of God".

Still, there must have been plenty of courage in reserve for the moment he had to break the news to his first wife that God had "told him" he had to stay at home studying the Bible, while she went out to work to support the family. Francis' eyes light up with all the sparkle of his pastoral charisma the moment I start to carry his cup of hot chocolate across the coffee shop.

"Wonderful, wonderful," he enthuses, as he sips the drink, before turning the conversation straight back to matters of faith.

"Are you born-again David?" he asks. But he doesn't seem too disappointed when I say I am not. He simply shakes his head, flashes that grin once more, and says, "Oh you really should, it's wonderful".

The conversation is carried out on a gentle level – as if he has simply asked me if I also drink hot chocolate.

"Yes, it's a wonderful thing," he adds, taking another sip of his drink. This time it's impossible to know whether he's talking about his faith or his hot chocolate.

Growing up in Lago, Nigeria, Francis was the second of six children. He attended a Muslim school but was brought up a Christian.

"But in those days I had not been born again, I had not received the Holy Spirit," he says. "I went to church every Sunday of course. But that was just a cultural thing. I did it because that's what we had always done. It didn't mean very much to me. I studied hard and I dreamed of becoming a doctor. I was offered a place studying medicine at Missouri University in the United States, but my family couldn't afford to send me there. So I came to the UK. The flights were cheaper. My sister was already living in London, and I had been offered a place on the Applied Biology degree course at Coventry University."

But when he got here, far from discovering science, he discovered religion.

"I didn't ask for it, but it came to me anyway," he says. "At the end of my first term, I was working in an industrial bakery in the holidays, and I was alone in the flour room in the middle of the night when God came to me.

"I heard the words 'even a child can have faith in God', spoken into my ear as clear as you are speaking to me now. I knew immediately that God was talking to me, and I got down on my knees – there and then in the dust of the flour room – and I prayed.

"I don't know how long I prayed for. Time seemed to stand still. It could have been hours. But when I opened my eyes, I felt I could see a halo above my head.

"In the weeks after that, God spoke to me a couple more times – saying I should forget medicine and take on the life of a preacher. I kept saying I will, as soon as I finish my degree.

"But when God spoke to me for a third time, I knew I must do as he said. So I left university behind."

Does he really believe that he has done more good for humanity as a street preacher than he might have done as a medic?

The question brings a momentary flicker of what seems like sadness to Francis' eyes. He pauses before he answers.

"Yes," he says at last. "God had his own plans for me. I was happy to trust in Him.

"Breaking the news to my father at home in Nigeria, on the other hand," he chuckles. "That was the difficult part."

Francis transferred on to a theology course at Bristol University, but was kicked-out at the end of his first year, after he dogmatically refused to discuss any theology or philosophy that he couldn't find directly referenced in the Bible.

"If it's not in this book," he says, patting his well-thumbed Bible. "If it's not in here, I'm just not interested."

After abandoning his second degree course, Francis was given a place on a theology diploma at a Baptist College in Woodland Road.

But even here, his particular brand of devotion got in the way of his studies. "Eventually I told the principal that God had told me to leave the college – that he would teach me all I needed to know in my own home. He took it very well – he told me God clearly had plans for me."

But God's home-study plans would prove to be the bane of the life of Francis' wife Elfrida.

"For much of the 1970s and 1980s, I spent all my time at home reading the Bible voraciously. God wanted me to do that, rather than go out to work. Elfrida realised that was my calling, and so she went out to work to support me and our two children," he says. "She was a wonderful woman."

Elfrida, an accountant, took the strain of being the family bread winner for years, until late in the 1980s when Francis finally took a position as a door-to-door salesman for Encyclopedia Britannica.

But Elfrida died suddenly in 1996, after suffering a brain haemorrhage.

"I'd had a dream a month before she died, in which she dropped to the ground and I tried to catch her, but couldn't. That was God warning me that I would lose her. I was grateful to Him for giving me that warning.

"I cried and cried when she died so suddenly, so young. But I never considered raging against God."

Two years later Francis remarried – Jacqueline, a lecturer at the City of Bristol College, who had been told in a dream that she would meet a preacher that she was destined to support.

It was a match made in heaven.

Francis has been running his own church since the mid-1980s, when he was – you've guessed it – told to set it up by God.

The Church Of The Body Of Christ aims to overcome sectarianism by bridging the gaps between different Christian denominations, and cutting out the pomp and ceremony of traditional churches. Francis' disciples simply meet in each others' front rooms.

"That was Jesus' idea of a church," he tells me, as he nears the end of his hot chocolate.

Now aged 66, Francis has reached the time of life when most of us start taking things a little easier. But he says he has no plans to stop preaching – he maintains his noon to 1pm session in Broadmead, six days a week, every week of the year.

"Sometimes I feel tired," he says. "But once I step into the middle of Broadmead, open my mouth, and start preaching again, I'm filled with a new energy – I am filled with the energy of the Holy Spirit. So I just carry on."