A secular education campaigner says as many as four in 10 state schools have religious content that tells children their friends can die or suffer because of their sin, or has parallels with child grooming.

Tanya Jacob is the South Island representative for the Secular Education Network, a lobby group currently campaigning to get the law around religious education in schools in line with existing human rights legislation.

Ms Jacob told The AM Show on Wednesday morning that "hundreds and hundreds" of schools currently have curriculum supporting unhealthy religious education.

"We are reaching out to parents to let them know what the religious instruction in their school is really all about. Generally the parents aren't told what's going on in their religious instruction classes - and often the schools don't know either," she said.

"The sorts of things they can have - and we're talking primary and intermediate schools - are things like telling children things like they can die, and their friends can die, and that people they care about can suffer terribly if they sin.

"Some of the content can be disturbingly similar to grooming. We're talking things like creating secrets in the class, and special friends."

Ms Jacob says the Secular Education Network is currently appealing to the Human Rights Review Tribunal to get the legislation around religious education in schools looked at.

She says if anything, she's the opposite of anti-religion, and is merely trying to ensure all religions get the same exposure - including non-religion.

"We are trying to allow all kids to have fair access to their schools - not promoting one religion over another and kicking the non-Christian kids out of their classroom and promoting that religion," Ms Jacob said.

"If you want to have religious freedom, you have to have everyone on an even playing field - not the school endorsing one religion."

Newshub.