Fairfax revealed this month that the Premier's office sought to fast-track a change to public school enrolment forms, removing the option for parents to select ethics class as an opt-out alternative to "special religious education".

Parents would instead be asked to nominate the religion of their child.

Educators, including primary school ethics teachers and lecturers in ethics and philosophy, have co-signed a letter warning that the change will discourage children from studying ethics.

"The study of ethics is challenging," signatories such as Macquarie University philosopher Neil Levy wrote in a letter to Mr Baird last week.

"Sometimes, however, the distinction between right and wrong is obvious. Hiding from parents the option of ethics classes as a substitute for scripture, for instance, is obviously wrong.

"[Parents] should be allowed to make the choice to opt into the ethics class, rather than having their child automatically enrolled in scripture class."

An enrolment form introduced last July tells parents that they can choose ethics classes when available and opt out of "special religious education".

Faith groups say the new forms are responsible for falling enrolment in religious education, also known as "scripture" classes, and have lobbied the government for it to be overturned.

The form has not yet been changed.

However, Fairfax revealed last month that the Premier's office sought to bring the changes forward from after the March election to late last year.

The government has denied it is part of a deal with Christian Democrat MP Fred Nile, an opponent of ethics classes and the crucial balance of power MLC.

A spokeswoman for Mr Baird said the Premier "is a strong supporter of both special religious education and special education in ethics".

The government says it monitors enrolment forms to ensure they align with its existing policy on ethics classes, a policy developed at a 2012 parliamentary report into ethics education.

That inquiry, which followed a bid by Reverend Nile to abolish ethics classes, concluded that parents should not be advised that ethics classes are available until after they have decided not to enrol their children in religious education.

Greens MLC John Kaye said the proposed changes were "a layer of deception designed to trick parents".

"The form will hand children over to religious proselytisers who bear no relationship to the values or beliefs of that family," he said.