[17] His books seek to give a biological and rational explanation of human behaviour[5] and include references to philosophical and religious sources.

[18] An article by Griffith published in The Irish Times summarised the thesis presented in Freedom: The End of The Human Condition (2016) as "Adam & Eve without the guilt: explaining our battle between instinct and intellect.

"[19] Kirkus Reviews wrote, "Griffith offers a treatise about the true nature of humanity and about overcoming anxieties about the world".

[20] The Templeton Prize winner and biologist Charles Birch, the New Zealand zoologist John Morton, the former president of the Canadian Psychiatric Association Harry Prosen, and Australian Everest mountaineer Tim Macartney-Snape[21] have been long-standing proponents of Griffith’s ideas.

As Professor Scott Churchill, former Chair of Psychology at the University of Dallas, said in his review of Freedom, 'Griffith's perspective comes to us not as a simple opinion of one man, but rather as an inductive conclusion drawn from sifting through volumes of data representing what scientists have discovered.'...

It was incorporated in 1990 with Griffith and his colleague, mountaineer Tim Macartney-Snape, among its founding directors and became a registered charity in New South Wales in 1990, known as the Foundation for Humanity’s Adulthood.

[26] In 1995, Griffith, Macartney-Snape and the Foundation for Humanity's Adulthood (the World Transformation Movement's name at the time) were the subject of an Australian Broadcasting Corporation (ABC) Four Corners program[4] and a Sydney Morning Herald newspaper article in which it was alleged that Macartney-Snape used speaking appearances at schools to promote the foundation, which was described as a cult, and that Griffith "publishes work of such a poor standard that it has no support at all from the scientific community".

[36] In 2020, an article by Griffith published in The Spectator Australia under the heading 'The science of bushfires'[37] about his biological analysis of the dangers of eucalypts in light of the 2019–20 Australian bushfire season resulted in him appearing on Alan Jones's 2GB radio program,[38] and on the Richo & Jones Sky News Australia television program.