The principals of dozens of Anglican schools in Sydney have written to federal MPs warning against changing anti-discrimination laws to protect LGBT teachers from being excluded by religious schools.

The group says the shift would undermine their faith's core values.

"Until such time as religious freedom is codified in legislation, the exemptions should remain," their open letter states.

The coalition vowed to protect LGBT students and teachers in religious schools after the findings of a review into religious freedom were leaked earlier this month, sparking furious debate about their rights.

Mr Tehan said the message from the 34 Anglican principals is part of a "very important discussion" about competing rights.

"Obviously the UN declaration of human rights has freedom of religion as one of it's core rights, but we also want to protect against sexual discrimination," he told Sky News on Wednesday.

He is confident Attorney-General Christian Porter, who is working on the government's response to the review, will address the issue.

"I've got great confidence that the attorney-general will get the balance right when it comes to these competing rights," Mr Tehan said.

Mr Porter will make recommendations to cabinet and is currently speaking with shadow attorney-general Mark Dreyfus, he said.

"They were close to a resolution when parliament last sat but they didn't quite get there, so those discussions will continue."

In their letter, the Anglican principals also warned of profound unintended consequences if key exemptions are removed from the Sex Discrimination Act for faith based educators.

Among who signed the letter are the principals of King's School at Parramatta, Barker College and Abbotsleigh in the northern suburbs, Shore at North Sydney and Trinity Grammar School in the inner west.

Australian Associated Press