TEJU HASSAN has come far, and so have most of his flock. Born near Lagos 50 years ago, he converted to Christianity as a young man and now ministers in the far north of Ireland to a multinational congregation. Like many a “reverse missionary” from the devout developing world to the secular north, he sees his task as repaying the lands that exported Christianity. “The Gospel was brought to Africa by English and Irish priests. White people also did bitter things, but we are still grateful for the faith and we are bringing it back.” His 100 followers are an outpost of Christendom’s fastest-growing segment: people who seek an ecstatic experience described as “baptism in the Holy Spirit” and insist that biblical feats, from healing to exorcism to speaking in tongues, should be part of present-day worship. They are sometimes described as “charismatic” or “renewalist”. Within this category are Pentecostal churches that stem from a revival begun in America over a century ago; subgroups within established churches, which after 1960 began worshipping in a similar way; and newer churches that use Pentecostal style and language, with a fresh stress on prosperity. This can mean offering business tips, involving the faithful in ventures or telling them that God will enrich them if they donate money.

Todd Johnson of America’s Centre for the Study of Global Christianity reckons that as of 2010, these charismatic worshippers amounted to a quarter of the world’s 2.3 billion Christians; by 2025 he expects their number to reach 800m (see chart). It is often noted by religion-watchers that Christianity globally is becoming more southern and exuberant. But the success of Pentecostalism and its imitators also highlights a more subtle point: the need for a kind of religion that is flexible enough to suit people in transit, whether between the southern hemisphere and the northern, between the countryside and the city, or between poverty and wealth.

Speaking in tongues

For uprooted peasants, too, coping with the anonymity of a megacity slum, charismatic churches provide a paradoxical blend of social support, discipline and emotional release. As Don Miller of the University of Southern California puts it: “Pentecostal worship is joyous, ecstatic and offers a sense of self-transcendence that fills a void in the lives of migrants—and exorcising demons, literally or metaphorically, can be a way of gaining control over individual or family problems.” Migrants travelling between countries need the same balance of solidarity and catharsis, and are well served by the loose structure of charismatic churches, which can spring up quickly wherever the need arises.

Pastor Teju’s is a typical tale. His chance to migrate came when the multinational firm he worked for as an accountant sent him from Lagos to England for training. Hearing that Ireland’s economy was booming (in 2000), he got a job there. As his career progressed, so did his spare-time role as a pastor with another successful multinational concern, the Redeemed Christian Church of God (RCCG), a Nigeria-based organisation that ministers to the country’s diaspora and all other comers.

His flock includes people from across Africa, and a few Irish looking for an alternative to Catholicism. His church claims to have thousands of communities worldwide. Though a prolonged slump means the pool of recruits in Ireland’s northwestern tip may be drying up, globally it seems on track. In Nigeria its Redemption Camp attracts millions to its annual meetings. A 10,000-seat stadium in Texas acts as a hub in America and last year David Cameron paid a pre-election visit to its London gathering, where the faithful cheered the prime minister as he lauded the family, the Bible and self-improvement.

“Our people are very practical,” says Pastor Teju. So too is his brand of religion. Like migrants in search of safety and prosperity, charismatic Christianity has proved adaptable, almost chameleonic. To people whose lives are in flux, it offers a mix of ecstasy, discipline and professional and personal support. In Brazil an initially sober kind of Pentecostalism has been replaced by a brasher kind (see article). In South Korea (see article), a style of worship that suited a poorish, insecure country has been replaced by one that flaunts success.

Whatever their style, Pentecostal pastors are culturally closer to their flock than are the learned clerics of the Catholic or Lutheran churches; and they are numerous. A study in 2007 found that in Brazil Pentecostal churches had 18 times more clerics per believer than the majority Catholics. As Mr Miller points out, older churches move slowly because they are lumbered with hierarchies and rules; the Pentecostal world is one of quick startups, low barriers to entry and instant reaction to change.

At worst, this flexibility shades into opportunism. In every country where Pentecostalism has thrived, its leading practitioners have faced investigations of their finances. In 2011 Forbes magazine estimated the combined worth of five Nigerian pastors as at least $200m. In Brazil the faithful seem tolerant of pastors who are light-fingered with their tithes; many see giving as a virtuous act, regardless of the money’s ultimate destination. Estevam Hernandes, one of Brazil’s best-known preachers, cheerfully resumed his career after returning, in 2009, from five months in an American jail for smuggling undeclared cash.

Some, though, have emerged unscathed. Last year Britain’s Charity Commission gave a clean bill of health to the British branch of one of Nigeria’s richest churches, the Winners’ Chapel. Or take Sunday Adelaja, a Nigerian-born cleric who is a player in the affairs of Ukraine. His Embassy of God church claims 25,000 followers (almost all white) in Kiev and outposts in over 20 countries. In 2009 he was questioned over the collapse of an investment firm which had touted for business in his church; he satisfied the police that he was not responsible.

In the past migrating religious groups either merged into their host societies or else pickled the culture of the old country in aspic. Thanks to technology, today’s roaming worshippers have no such dilemma; a Nigerian or Brazilian in transit can adapt while maintaining contact with home. Globally dispersed Pentecostal churches meet both those needs. An outlying branch of the RCCG can offer job advice and a way to keep links with home. Global charismatic movements act as transmission belts along which ideas and worship styles can travel quickly. “A hymn can be composed in one continent and sung in another a few days later,” says Allan Anderson of Birmingham University.

Like water, charismatic religion takes the path of least resistance. Philip Jenkins, a scholar of global Christianity, cites several little-noticed examples. Dubai is now a bastion of Pentecostal-style worship, among migrants; the Muslim authorities do not mind as long as local Emiratis are not proselytised. Thanks to a shared language, Brazilian neo-Pentecostal churches do well in Angola and Mozambique. And though Filipino Christianity is almost entirely Catholic, the export variety, adapted to the diaspora’s needs, is intensely charismatic, offering a combination of mysticism and practical advice. One movement, El Shaddai, claims 8m members across the world. Worshippers at its Manila base wave their passports in the air as they pray for successful travels.

Politically, too, Pentecostal churches tend to be pragmatic rather than consistently conservative. Brazil’s globally successful Universal Church of the Kingdom of God (UCKG) initially resisted the rise of the centre-left Workers’ Party, but went on to back its presidential candidates, including Dilma Rousseff, the incumbent. In Ukraine Mr Adelaja was close to the 2004 Orange revolution but also wooed the pro-Russian president, Viktor Yanukovych. Peru’s right-wing authoritarian leader, Alberto Fujimori, enjoyed Pentecostal support, but in El Salvador, Pentecostal preachers strike a leftist tone. In America Latino Protestants (mostly charismatic) are contested electoral terrain. Almost all Pentecostal churches are anti-abortion and anti-gay, but the UCKG has made statements that are pro-choice and comparatively gay-friendly.

Predicting the future of such a volatile phenomenon is difficult. But wherever people are on the move, and are culturally receptive to Christianity in some form, charismatic religion will surely follow.