Dr Thompson said even the Pentecostal churches, which deliberately used contemporary forms of worship and communication, had very high turnovers.
"This means that they growth needs to be treated with a certain amount of scepticism."
Catholic was now the largest Christian denomination, with 492,105 adherents, overtaking the Anglicans for the first time in 2013.
One in eight people affiliating with the Catholic faith, or 61,242, were Asian and one in 10 belonged to a Pacific ethnic group.
Money and faith
The Herald investigation found that there was a strong correlation between wealth and religion.
In Auckland, Favona South, Mascot (Mangere) and Wymondley (Otara) - areas ranked most deprived by the index - were the most religious neighbourhoods, where more than 90 per cent of people had at least one religion.
By contrast, richer suburbs such as Grey Lynn, Ponsonby and parts of Devonport, had more than half of the residents not affiliated to any faith.
Waitakere West and Karekare, ranked among the least deprived areas, are Auckland's least religious neighbourhoods where about 65 per cent of residents declared themselves to be non-religious.
Massey University expert in religion Peter Lineham said an increasing number of New Zealanders no longer found religion appealing.
"Individualism is a powerful feature of modern middle-class society and the idea of a religion and its values to conform to doesn't appeal," said Professor Lineham, a religious historian.
However, he said, poor people stood to benefit from being members of a church or an organised religion.
"Religion offers a lot of benefits for poor people, in a sharing community, comfort and support in difficult times, and with significant financial benefits to share," said Professor Lineham.
"In essence, one appeal of religion is to deal with the isolation of migration and secondly it is a way to reinforce the values of an ethnicity."
Role of immigration
Professor Lineham said immigration contributed to the growth of religiosity in the region.
"Auckland is the most religious because it is the New Zealand born who have very high levels of non-religion and indeed disaffiliation from religion," he said.
"Pasifika are a major factor but so are most migrant groups."
Catholic migrants, from countries such as the Philippines and India, had made Catholicism the most popular Christian denomination for the first time with 492,000 followers.
Except for Pentecostal and smaller evangelical churches, most other mainstream churches saw sharp drop in numbers.
AUT University Professor for Diversity Edwina Pio said wealthier individuals "may be spiritual without being religious".
This was because the rich did not need the networking and infrastructural support provided by churches, mosques, temples and gurdwaras.
Sociologist Paul Spoonley said New Zealand's skilled and economic migration policy targeted applicants from countries that had lower levels of religious affiliation.
"Skilled migrants tend to be educated, middle class people in countries similar to New Zealand with low levels of religious affiliation, and we have also sourced them from countries that are not religious, such as China," said Professor Spoonley, also from Massey University.
"In contrast, some of the more religious communities tend to come in the humanitarian categories as refugees or as part of chain migration from the Pacific, and have fewer educational credentials or work skills."
The most diverse suburb
These poorer, more religious migrants, would usually look to settle in areas close to a place of worship or church of their faith.
"For many new immigrants, being near a temple or a church is actually important and dictates where an immigrant community will settle," Professor Spoonley said.
"Churches are a central and very influential institution in terms of settling new migrants ... they have played a key role in helping welcome immigrant communities and providing them with a ready-made like minded community."
Mt Roskill, once known as the Bible belt of Auckland, is now probably the city's most ethnically and probably also religiously diverse suburb.
Christians are now the minority there, on just 44 per cent, but 10.5 per cent identify as Hindu and about 6 per cent as Muslim.
Areas with the suburb, Walmsley and Wesley, had the highest percentage of Muslims in the country on 18.2 per cent and 13.2 per cent respectively.
Nearly 60 per cent of Mt Roskill residents were Asian-born, the highest proportion in New Zealand, and just about a quarter of the population are European.
Migrant religions such as Hinduism, Islam and Sikhism have grown significantly.
There are now about 89,000 Hindus in New Zealand, an increase of 16,000 over a period in which the Indian population here grew by 50,000.
The highest concentration of Hindus lived in Lynfield North, where a quarter are affiliated to the religion, and one in 10 residents in Mission Heights and Ormiston are Buddhists.
The most Christians can be found in the areas of Wymondley, Harania North and Otara where about eight in 10 declared themselves as being affiliated to the faith.
Statistics New Zealand reported that about 80 per cent of the largest non-Christian religious groups, except for traditional Maori faiths, Judaism and Baha'i, comprised of mainly new immigrants who arrived since 2000.
The Queenstown-Lakes District had the largest percentage change of religious diversity, with a 658 per cent growth in Hindus, 367 per cent increase in Muslims and 151 per cent more people professing to have no religion.
'Target the rich'
Businessman Ron Barker, a former Catholic, says churches should change its message and "target the rich", if they wanted to grow their flock.
A Herald investigation found residents in high-income New Zealand suburbs are less likely to identify with a faith, and Christianity had suffered a sharp decline.
The number of Christians decreased to 1,906,398 (48.9 percent of people with religious affiliation) from 2,082,942 (55.6 percent) in 2006.
Mr Barker, who identified himself as a "Born Again Christian" in the last Census, said he attends churches that preach "prosperity gospel", such as City Impact in Auckland.
He stopped attending the Catholic church because he felt its message was no longer relevant in the 21st century.
Affiliations to some Christian religions had increased, including Evangelical, Born Again, and Fundamental (up 11.2 percent) and Adventist (up 5.5 percent).
"As society gets better off, churches need to change their message to target the rich to remain relevant," he said.
Prosperity gospel preaches that financial blessing is the will of God for Christians, and that faith, positive speech and donations to Christian ministries will increase a believer's material wealth.
Mr Barker, who claims to be a successful businessman, said churches could be turned into places where the rich could network too, rather than just be institutions that provided support for the poor.
How the map works
Use the interactive map to see the breakdown of religion in your suburb. Hovering/ tapping over an area will reveal the breakdown for main religions.
Use the links on the left to navigate directly to the major cities in the country.
Dark blue indicates areas where more than 60 per cent of people said they had no religion. Yellow indicates an area where there is a strong religious population.
If you click on Wellington, you will see the city is predominantly blue or dark blue. In Auckland, there is a mix of dark blue areas - mainly in the central suburbs - and bright yellow - mainly in south and southwest Auckland.
App readers: Tap here to explore the interactive
