Mr Prosser's argument does not withstand a moment's scrutiny. At different times in human history, different groups of different ethnicity have misguidedly concluded that the only cure for their woes is to engage in mindless bursts of killing.
They are not distinguishable by the colour of their skin or their religion, but by their fanaticism and intolerance of other ways of life and points of view.
Mr Prosser knows that. He is not an idiot, as his belated apology shows. He understands it is not fair, practical or logical to penalise all Muslims for the sins of a few. He just chooses to pretend he does not for the sake of pandering to the simple-minded who think good and bad are only skin-deep.
The question for Mr Peters is, is he prepared to provide a harbour for such cynical and damaging politicking. Leadership is about more than looking noble and put upon at the same time.
Unfortunately, nothing in Mr Peters' political past suggests he is about to take a principled position. Populism and pandering to the ignorant are his stock and trade. It is not that long ago that he was alarming his followers with talk of an Asian invasion.
Mr Prosser's cynical scapegoating of a religious minority runs counter to the New Zealand ethos of fairness and tolerance. He is not a fit representative of either the community or the country.
NZ First should kick him out of the party. Whether they do or not will show whether they condone their colleague's descent into the political gutter.
No additional comment is required.