Wellington, Dec 17 - A billboard outside an Anglican church depicting Joseph and the Virgin Mary in bed, with the words "Poor Joseph, God was a hard act to follow", has upset Catholics in New Zealand, according to news reports Thursday.

"The suggestion is that the two have just had sex," the New Zealand Herald reported, quoting the vicar of Auckland's St Matthew's-in-the-City church, Archdeacon Glynn Cardy, as saying it was designed "to provoke thought and conversation about the true origins of Christmas".

But Lyndsay Freer, spokesperson for New Zealand Catholics, told the paper: "Our Christian tradition of 2,000 years is that Mary remains a virgin and that Jesus is the son of God, not Joseph.

"Such a poster is inappropriate and disrespectful."

Cardy said: "Progressive Christianity is distinctive in that not only does it articulate a clear view, it is also interested in engaging with those who differ.

"Its vision is one of robust engagement."  (dpa)