Delays in the release of the Federal Government's review into religious freedom are sparking outrage from critics, including former High Court Justice Michael Kirby.

Mr Kirby says secularism in Australian education is at threat, and as the Government have not yet released the Ruddock Report, the basis for giving private religious schools more money, and developing policy, should be considered questionable.

The Morrison Government in September announced a $4.6bn commitment to Catholic and independent schools across the country, with $680 million going to Queensland schools.