"I know that the faiths don't condone or believe that, so what the statement does is it draws a line under that. It says in the most public way possible that no faith in New Zealand condones violence towards women or children."
New Zealand had the sixth-highest rate of child deaths from maltreatment in the developed world in a Unicef league table in 2003. Three years later outgoing Governor-General Dame Silvia Cartwright described family violence as our "dark secret".
Dr Zain Ali, Fiji-born head of Auckland University's Islamic Studies Research Unit, said the issue had troubled him for a long time and when another horrific case hit the media two years ago he contacted two Christian ministers to suggest a joint prayer service for the victims.
"I have children, I get angry at my children, but not to the point where I abuse them or strangle them or burn them with cigarettes," he said.
"At a certain point you struggle to hold back the emotion; I wondered if there was something I could do."
His friends, Maori Anglican minister Rob McKay and Auckland University chaplain Uesifili Unasa, a Methodist, suggested a more ambitious approach and organised a meeting of several faith groups with Dr Wills.
Dr Wills' office helped the group to contact other religious leaders and to rewrite the joint statement until a final version was agreed.
The statement recognises family violence is "one of the most significant moral, social and spiritual challenges that we face as a country" and declares that it is "never justified".
Mr Unasa said the statement was not just "stating the obvious".
"From a Christian point of view, scripture is sometimes interpreted to condone and actually make it okay to behave in a violent way," he said.
Parents often quoted a verse from Proverbs: "Whoever spares the rod hates their children, but the one who loves their children is careful to discipline them."
Mr Unasa said a story about Jesus clearing moneylenders out of the temple was also "often quoted in Pacific churches as being the reason why you need to use violence".
"The whole of the Old Testament is about war and violence and bloodshed and that sort of thing, and it is okay according to the biblical interpretation of some of our Pacific churches to actually exercise violence as if it were God-ordained.
"This is part of the reason we think the national statement by the leaders and faiths is so critical."