“Ha-lleluuuu-jah,” booms the distinctive voice of Pastor Enoch Adeboye, also known as the general overseer.

The sound comes out through thousands of loudspeakers planted in every corner of Redemption Camp. Market shoppers pause their haggling, and worshippers – some of whom have been sleeping on mats in this giant auditorium for days – stop brushing their teeth to join in the reply.

Hallelujah is the theme for this year’s Holy Ghost convention at one of Nigeria’s biggest megachurches, and all week the word echoes among the millions of people attending.

As evening falls on Friday, Adeboye, a church celebrity, is soon to take the stage at his vast new auditorium to give the convention’s last, three-hour sermon. Helicopters land next to the 3 sq km edifice, delivering Nigeria’s rich and powerful to what promises to be the night of the year.

Thousands of worshippers surge up the hill towards the gleaming warehouse. Shiny SUVs, shabby Toyota Corollas and packed yellow buses choke the expressway all the way from Lagos, 30 miles away.

The congregation prays during the Redeem Christian Church of God’s annual Holy Ghost convention

But not everyone has to brave the traffic. Many of those making their way to the auditorium now live just around the corner. The Redeemed Christian Church of God’s international headquarters in Ogun state has been transformed from a mere megachurch to an entire neighbourhood, with departments anticipating its members’ every practical as well as spiritual need.

A 25-megawatt power plant with gas piped in from the Nigerian capital serves the 5,000 private homes on site, 500 of them built by the church’s construction company. New housing estates are springing up every few months where thick palm forests grew just a few years ago. Education is provided, from creche to university level. The Redemption Camp health centre has an emergency unit and a maternity ward.

On Holiness Avenue, a branch of Tantaliser’s fast food chain does a brisk trade. There is an on-site post office, a supermarket, a dozen banks, furniture makers and mechanics’ workshops. An aerodrome and a polytechnic are in the works.

And in case the children get bored, there is a funfair with a ferris wheel.

A funfair located inside the Redemption Camp

‘The camp is becoming a city’

Set up 30 years ago as a base for the church’s annual mass meets, as well as their monthly gatherings, Redemption Camp has become a permanent home for many of its followers. “The camp is becoming a city,” says Olaitan Olubiyi, one of the church’s pastors in whose offices Dove TV, the church television channel, is permanently playing.

Throughout southern Nigeria, the landscape is permeated by Christianity of one kind or another. Billboards showing couples staring lovingly into each other’s eyes, which appear at first glance to be advertising clothes or condoms, turn out to be for a pentecostal church. Taxi drivers play knock-off CDs of their favourite pastor’s sermons on repeat, memorising salient lines.

“I’m a Winner,” read the bumper stickers that adorn the fancier cars, declaring their owners’ allegiance to Winners’ Chapel, a grand white megachurch whose base, Canaanland in the Ota region, is all neat fences and manicured lawns.

“Where I’m from, people long for tractors to farm with. Here they just use them to cut grass,” exclaims one visitor, driving through Heaven’s Gate. It is a world away from the throng of people, fumes and rubbish outside.

One of the Nigerian commercial banks operating in the camp

Canaanland has banks, businesses, a university and a petrol station – one of a number of churches beginning to offer these services.

But none can match Redemption Camp for scale. Daddy GO – as the charismatic Adeboye is affectionately known by his followers – has been perfecting the package for the past decade.

“If you wait for the government, it won’t get done,” says Olubiyi. So the camp relies on the government for very little – it builds its own roads, collects its own rubbish, and organises its own sewerage systems. And being well out of Lagos, like the other megachurches’ camps, means that it has little to do with municipal authorities. Government officials can check that the church is complying with regulations, but they are expected to report to the camp’s relevant office. Sometimes, according to the head of the power plant, the government sends the technicians running its own stations to learn from them.

There is a police station on site, which occasionally deals with a death or the disappearance of a child, but the camp’s security is mostly provided by its small army of private guards in blue uniforms. They direct traffic, deal with crowd control, and stop children who haven’t paid for the wristband from going into Emmanuel Park – home to the aforementioned ferris wheel.

Mechanics attend to a 25-megawatt gas turbine plant that powers the camp

Comfort Oluwatuyi is a food trader in the Redemption Camp market. She says she pays a very low rent for her little lock-up shop and can make up to 10,000 naira a day in profit – much more when a convention is on. The market formed seven years ago, when women in the camp petitioned “Mummy GO” – Adeboye’s wife, Foluke – to build it so they would not have to cross the eight-lane expressway every time they needed some tomatoes.

Oluwatuyi’s 10-year-old daughter, Emmanuelle, helps her pour palm oil into plastic bottles and stack potatoes in tin dishes. Emmanuelle and all her siblings were born here. “It’s quite possible for a child to be born in this camp, grow up and be educated here, and then live here,” Pastor Olubiyi says.

Outside the Holy Ghost convention, Redemption Camp has the peaceful surroundings and conveniences of a retirement village – in large part because the power plant, fed by its own gas pipeline from Lagos, removes the need for the constant thrum of diesel generators.

“My generator is on vacation. In the morning, I can hear the birds sing,” says Kayode Olaitan, a retired engineer who moved his family here from Lekki, one of Lagos’ most upmarket areas, two weeks ago. He loads his pink-frocked granddaughter into the car, ready to drive to the all-night service.

Olaitan’s neat £78,000 bungalow has been built on what used to be a swamp. Workmen are scraping up concrete from the paving slabs, putting the finishing touches to the 75 identikit houses on Haggai Estate Nine.

Comfort Oluwatuyi selling palm oil in a grocery shop in the camp market

Haggai, the church’s property developer, is named after the prophet who commanded Jews to build the second temple of Jerusalem. Almost all the houses on Nine have been sold, and Haggai is about to move on to Estate Ten. There is no perimeter wall around Redemption Camp, so it can expand indefinitely.

It’s quite possible for a child to be born in this camp, grow up and be educated here, and then live here Pastor Olubiyi

Mortgages are arranged through Haggai bank, headquartered in Lagos. There has been a knock-on effect on surrounding areas: in some cases, the price of land near Redeemed Camp has increased tenfold over the past decade.

For years, people have owned houses here to stay over after conventions and the monthly services. But increasingly, families like the Oliatans find themselves wanting to live full-time with people who share their values, in a place run by people they feel they can trust. “We feel we’re living in God’s presence all the time. A few days ago, Daddy GO took a prayer walk around here,” Oliatan says.

While you have to be a Christian and a church member to buy and live on site, there is no such requirement for doing business. The FCMB bank is one such business that has set up shop here, with bright white mock-Corinthian columns installed just behind the auditorium.

A line of traffic leading to the Redeemed Christian Church of God auditorium

Outside, a young woman in elaborate sunglasses and a polo shirt with “MILLIONAIRE” emblazoned on the chest has persuaded Tayo Adunmo to open an account. The bank employee is normally based in Lagos, but has been at Redemption Camp for Holy Ghost week, and says she has signed up 500 people already.

Adunmo already has a bank account, but decided to open another because the minimum withdrawal amount is 200 naira (about 55p) – a fifth of the minimum at her current bank. She’d love to live in the camp, she says, but can’t afford it unless she finds work there.

Like all the other businesses on site, banks are attracted by the infrastructure and the sheer numbers in attendance – it’s like having a stall at a music festival. But the tentacles of the Redeemed Christian Church of God reach much further: it says it has five million members in Nigeria, and more at its branches in 198 other countries. “It’s in virtually every town in Nigeria, and that means some business,” Olubiyi says. “Anywhere you have two million people congregating, banks are interested.”

This also means business for the church, of course. Daddy GO’s private jets don’t appear out of thin air, though there is plenty of cash flowing in from collection plates – which these days are often just card machines.

Religious institutions are tax-exempt in Nigeria. Redeemed authorities say that its income-generating arms pay tax, but it is hard to say where these end and the church begins. In any case, the church has powerful members, so it would take a brave tax-collector to look deeply into its finances.

Pastor Adeboye, the general overseer of the Redeem Christian Church of God, is projected live on big screens during the annual convention

In fact, Daddy GO is a former mathematics lecturer, and has clearly not lost his head for figures. He is constantly dreaming up new enterprises – including a printing press, hundreds of holiday chalets on the site and a church-owned window manufacturer, which imports the components from China and assembles them to sell or use in camp projects.

“This is our peak period. We have produced 200,000 copies of different books and magazines in the past three months,” says Ben Ayanda, head of Redeemed’s press, dressed in a bright yellow and green tunic and matching trousers.

He plucks Daddy GO’s Gems of Wisdom Part V from a pile of papers. “If you bring anything less than the tithe of all, you miss the blessings because He is very good in mathematics,” one line reads.

At the convention, the last stragglers hurry past the hawkers selling Hallelujah handkerchiefs and a billboard advertising Hallelujah cooking gas, to be there when the headliner comes on.

You can usually tell when Daddy GO is about to appear – he is preceded by his personal saxophonist.

Finally, the man who keeps the money coming in, who gives this entire neighbourhood its raison d’être, the de facto mayor of what is effectively an entirely new piece of city, takes his place on the vast stage and picks up the mic. The 75-year-old Daddy GO wears a grass-green short-sleeved suit, bow tie and gold watch. After praying on his knees at the lectern, he climbs to his feet.

“Will somebody shout Hallelujah?”

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