Four out 10 Kiwis now declare themselves non-religious, putting us firmly among the most secular countries in the world.

Census 2013 figures released yesterday show any claim to a Christian majority in New Zealand is shaky, with fewer than 1.9 million people affiliated with a church, down from more than 2 million in 2006.

Victoria University professor Paul Morris, who specialises in religious studies, said the country was in "new territory", with Christianity losing its central position in society.

"For the first time since 1901, Christians are not the clear majority."

The shift even raised questions about the appropriateness of Christian public holidays, such as Christmas, and the place of the church in schools.