The Secular Education Network is calling for religious education to be scrapped from primary schools, and to just be taught in high schools.
Controversy has been brewing over the issue this week, after an Auckland primary school scrapped religious classes when parents complained to the Human Rights Commission.
"The harm is that it's totally monocultural," David Hines from the Secular Education Network told Firstline.
"What's happening in schools now, it's not education, it's a promotional programme."
Mr Hines, a former Methodist minister, believes teaching Christian education in schools is actively putting down other religions.
"I looked through the syllabus and the lecturer notes for these classes - every one of the first 18 lessons this year for five-year-olds is about God," he said.
As the number of non-religious and non-Christian people continues to grow in New Zealand, Mr Hines is calling for religious classes to be cancelled at a primary level.
"In New Zealand a lot of people are just not interested in religion, so I would not say it's so important that it should be on a primary school [level].
"I would prefer to see it in high schools where kids who are interested in religion can opt in and get a really educational approach," he believes.
Mr Hines says he was unaware until recently how much of a "put-down" religious education is for non-Christians.