Brian Tamaki has found an unlikely supporter in the Mayor of Waitakere City.

In a letter to the New Zealand Herald this week Bob Harvey compares the Destiny Church leader to the founders of the Salvation Army and Martin Luther, spearhead of the Protestant Reformation.

Harvey said he does "anything to cheer on people who are turning people's lives around".

"People are trashing, shaking and beating children at unprecedented rates," he told the Herald on Sunday.

"This guy [Tamaki] is saying 'well I've turned around 700 men'. It isn't bloody women that are doing this. It's men. It's my brothers, brown, black or whatever. That's who's doing this. I didn't see too many women standing up in the Destiny Church with their hands on their breasts saying 'I won't do it', 'cause they ain't doing it.

"I'll be sleeping easier in my bed now that 700 robbers have sworn they'll never do it again."

The "Catholic boy" wasn't bothered that Cultwatch director Mark Vrankovich, among others, believes Tamaki is demonstrating cult or king-like symptoms, including indoctrinating and isolating his congregation.

"Well, so what? I think most churches have cults, don't they?" Harvey said.