Bishop Brian Tamaki has raised the stakes with his Destiny Church followers, exhorting them to leave behind houses, jobs – even family members – to join him at a "City of God" he is building in South Auckland.

At the church's annual conference in Rotorua on Friday night, Tamaki spent his entire two-hour sermon talking about how God had told him to build the city and why his followers had to lose their "parochialism" towards their home areas, even if it meant leaving behind loved ones.

Cult expert Mark Vrankovich said the speech was designed to "soften up" Tamaki's followers and the real pressure to move to South Auckland would come with one-on-one sessions with local pastors.

"Saying that the church family is more important than your physical family, that you must go with the spiritual family, is a classic cult idea. This will put great pressure on families and break up families."

Vrankovich was also concerned that Tamaki appeared to be encouraging people to sell their homes. "They'll be pressured to give the money from the house sale to the church, and they'll never see it again. He's extracting money from people for his dream, and something that he will effectively own. He wants to be mayor or king of this 'city' so he's softening them up to get them to move [to Auckland] so he's guaranteed not to be losing money on the deal."

Tamaki announced at a New Year's Eve service that Destiny Church had permission to build schools, a university and a massive auditorium at a property in Wiri, which he calls the "new Jerusalem".

The church has put its Mt Wellington headquarters up for sale to help fund the move, which is due to happen in December. It hopes to get more than $5 million from the sale.

It is unclear if people would live on site or nearby.

Tamaki said he would unveil more details throughout the weekend. People were encouraged to give generously and buckets were passed around even before Tamaki took the stage.

He was welcomed to the stage by a kapa haka group, which did a haka describing Tamaki as "the mouthpiece of God" and a "prophet".

Tamaki said God had spoken to him through the Book of Hebrews telling him to build a city. In Abraham's time people lived in tents in the desert, but Destiny members had to leave behind their "tent mentality" and aim for something "far bigger, far greater ... a City of God".

He acknowledged that when he first raised the idea five years ago, it "sent the movement into a tailspin. Some people even left".

But they were stuck in a rut, and had a "tent mentality", meaning they were wedded to the idea of many different Destiny Churches around the country.

"I fought for 10 years, seven of those just trying to change the parochial spirit of my pastors and ... we had to let some go or I had to tell some 'go away', because God is building a church that's one – one vision, one people, one direction."

Tamaki said parochialism would "sabotage city-building" and people had to give up their loyalties.

"People get a funny, wee strange loyalty to a house. [People say] 'This is the house my parents grew up in. I can't leave here, this is my family.' Well if you can't, you can't, but, bye bye, we're going."

He said reluctant family members would see what a great thing had been built "and want to come too".

Vrankovich said the New Testament spoke of the need to put families first, and nothing Tamaki was saying was biblically correct.

Tamaki said if people felt uneasy about his plan, "cool, just keep coming back tomorrow and the next day, and you'll see God's masterplan".