Catholicism only mainstream church experiencing growth, especially among ethnic minorities, as study shows other Western religions, such as Anglicanism, 'fail to connect' with diversifying cultures.
Maori and European converts are helping a controversial Muslim community grow in Auckland.
The Ahmadis, who are not considered Muslims by mainstream followers of Islam, have grown from just 20 members in 1987 to 350 today.
Among its members are those who identify as Maori, Pasifika and European New Zealanders.
Christopher Bradley, 20, who converted to the faith last year, said he first became interested in Islam after coming across a copy of the Koran at a city library.
"Out of curiosity I picked it up and started reading it, and I just couldn't stop. I was really interested, I was hooked to it," he said.
"All I knew about Islam at that time was from the media and television, and everywhere you hear about and everything that people talk about Islam is this whole terrorism, 9/11 thing."
Mr Bradley, a University of Auckland undergraduate, said he was drawn to the Ahmadi community rather than mainstream Islam because of its more peaceful views on jihad, or holy war.
Mr Bradley was raised a Catholic, and said he had been through a difficult childhood, especially after the death of his mother when he was 6.
"I began seriously looking for the meaning in life, and began searching for God after I left high school," said Mr Bradley, who now goes by the name of Ibrahim.
Prayers five times a day and reading the Koran are now part of his daily life, and since his conversion, he has been through two Ramadans where he fasted from dawn to dusk.
Cleric Shafiq Ur Rehman said Ahmadis practised Islam in its pristine form, just as the Prophet Muhammad himself did.
Views on the death and return of Jesus and the concept of the holy war were some of the differences it had with followers of mainstream Islam.
"We believe that we are leading the revival and peaceful propagation of the religion," the missionary said.
The community has been active in engaging with Aucklanders, including having the Koran translated into Maori and being present at weekend markets to distribute information about the faith.
In several Islamic countries the Ahmadis are marginalised and prosecution and systematic oppression have forced many to emigrate and establish communities elsewhere.
They were among the earliest Muslim communities to arrive in many Western countries, including Britain.
Islam is the third fastest growing religion in New Zealand and its growth in Auckland is twice as fast as elsewhere in the country.
From 0.001 per cent of the population in 1986, Muslims made up nearly 1.8 per cent of the city's population in 2006.
Javed Khan, senior vice-president of the Federation of Islamic Associations, estimates the number of Muslims in New Zealand to be between 50,000 and 60,000.
Like Christianity, Islam in New Zealand has a number of different denominations.
Many here are Sunni Muslims who follow the Shafii, Hanbali, Hanafi or Maliki schools of religious law, while there are others belonging to the Shia denomination.
The Ahmadis are in the process of building the largest mosque in Auckland, at Manukau, and say all Muslims will be welcome to use it for prayers - an offer unlikely to be taken up by the majority.
The Immigration Act 1987 radically changed the criteria for migrant entry to New Zealand, resulting in a surge in people coming from non-traditional source countries. This week, the Herald looks at how these migrant communities have changed Auckland.
Yesterday: Population - the changes and how comfortable are we?
Today: Religion - Christianity vs new religions
Tomorrow: Food - from caffe latte to teh tarik
Thursday: Sports - tapping on migrant talent
Friday: Festivals - changing the way we celebrate.