Parents Victoria yesterday passed a motion at its annual general meeting calling for the religion classes to be moved outside the normal school day.
The Education Department forces primary schools to run the classes during school time if an accredited instructor is available.
About 96 per cent of special religious instruction in Victoria is provided by Christian organisation Access Ministries, whose volunteers run the classes in 850 of the state's 1300 government primary schools.
Parents have always been able to opt their children out of the classes but many say they feel upset about being excluded and are bored by the alternative activities provided.
The government is already under pressure to change the contentious policy, with a case still before the courts alleging the classes are discriminatory and segregate children on the basis of religion.
Psychologist Sophie Aitken and two other parents, whose names are suppressed, have asked the Victorian Civil and Administrative Tribunal to order that the classes be held outside school hours. Judge Timothy Ginnane is yet to give a ruling on the case.
In information circulated to its members, Parents Victoria said special religious instruction classes may not be compulsory, but required families of minority religions or no religion to withdraw their children from class.