A Victim Support worker joked about hitting his children during a talk at Destiny Church.
The worker was filmed making the comments at a Sunday gathering in late February.
In the video, he tells the congregation, who can be heard laughing on the recording, about smacking his kids.
"Some of you have heard my story. I had a cane; I had a long cane.
"When the law says don't smack your kids well, I broke the law.
"I had a cane. Bend over, whack!
"The other son comes. Bend over, bend over, stop lifting your head, whack!"
He then goes on to joke about smacking one of his children more for resisting punishment.
"OK, you're going to get another one. Up and down, whack! Whack! You got three, son, because you kept going up and down.
"You're like a yo-yo!"
Independent victim advocate Ruth Money said the video was "absolutely shocking".
"It's an elder of Destiny Church bragging about harming his children. It's illegal to hit your children."
She said it would be bad enough if the person concerned was a volunteer liaising with vulnerable people, but for a person working in an organisation that is supposed to help the vulnerable it was "absolutely disgusting".
When approached by RNZ, Victim Support said it was recently made aware of the video and had "immediately taken steps to commence an investigation into the matter".
"Victim Support does not condone the statements in the video," chief executive James McCulloch said in a statement.
"We strive to support and empower victims, including victims of physical violence and it is essential that all our team uphold our values."
Money said it was hoped an independent investigation, its findings still secret, two years ago had improved systems at the taxpayer-funded charity.
"We've been down this path before with Victim Support for many years. Victims and the staff at Victim Support deserve a lot better than, 'We've immediately taken steps to think about doing something.'
"I understand that natural justice needs to prevail, however, I would hope that an inquiry happens immediately. That would have been the only appropriate response."
Destiny Church referred RNZ to the man, who said he would not be making any comment as the situation was in the hands of his employer and under investigation.
