THE Toowoomba man challenging the Federal Government's school chaplain's program said it had grown into a "behemoth" outside the High Court on Tuesday.
Ron Williams was presenting his second challenge to the Commonwealth's funding of the chaplains program in another landmark legal case.
While the first case, challenging the Constitutional validity of the Commonwealth funding such programs was upheld by the Court in 2012, the previous government passed urgent legislation to make sure it could continue.
Originally put in place by former Prime Minister John Howard, the chaplains program funds community religious leaders to provide schools students with advice.
But Mr Williams told reporters on Tuesday he was opposed to the idea of the Commonwealth funding such a program in schools.
He said he believed there was "no place in public schools for any form of missionaries", and that opposition to religion in Commonwealth-funded schools was what the case was about.
Mr Williams' original case in 2012 has previously been cited as one of the reasons behind a significant delay to a referendum on recognition of local government in the Constitution, a vote on which was prevented by former Prime Minister Kevin Rudd's decision to call an early election last year.
But the latest case could again threaten a raft of Commonwealth funding programs for schools, councils and community groups, as it challenges the legal basis for such direct grants to be made.
Hearings are set down for another two days at the Court in Canberra this week.