The main sources for the views of the Society on fundamentalism are the Treatises on Morality and Tolerance and the Essay on God . Of these the Treatise on Morality is the more important for an understanding of this subject. The Treatise distinguishes between the view of the Society on individual moral accountability, and that commonly adopted by other belief systems. In earlier beliefs adherents and followers expect to answer for their decisions, actions and conduct in life to some external authority or entity, be it God in any of his various manifestations, or any of his many alternatives and competitors. Members of the Society of HumanKind however, accept that if the Aim of their Society is achieved they will have to answer directly and in person to those who are affected by their actions and behaviour. They also recognise that they will spend eternity in the company of those who might be harmed by their decisions.

    Present-day fanatical fundamentalists believe that they will have to explain themselves only to their god. Realisation of the Aim of the Society of HumanKind will bring a new era in which every moment and place in human history can be visited and exhaustively examined by every member of all generations of our species, and where no concealment or prevarication is therefore possible. Under those conditions extremists and all fanatics will have to account for and justify their actions and decisions, not to some transcendental power or unearthly entity, but to the whole of a reunited humanity, including and especially their victims.

    Yet that wide difference of view on questions of personal moral accountability does not lead the Society of HumanKind to oppose all aspects of fundamentalist belief. On the contrary, the Treatise on Tolerance imposes a duty on the Society to foster and support any and all sincere belief, including therefore, those of fundamentalism. The Treatise concludes that pursuit of its Aim requires the Society to encourage rather than suppress difference between groups of humankind and amongst individuals, since diversity in humankind is our most valuable characteristic as well as our greatest source of strength.

    The Treatise on Knowledge extends that positive and welcoming view of difference and diversity among humankind by the Society to ideas and beliefs. This Treatise sets out how an acceptance of the First Axiom leaves no ultimately reliable basis for any of our knowledge. In that world of uncertainty our best hope of solving the problems we face is to apply as wide and diverse a range of opinions and ideas as we can to them. So diversity in ideas and opinions is, like all other differences between us, welcomed and encouraged by the Society of HumanKind.

    Indeed, the tolerance of the Society for other belief systems goes even further. The Essay on God concludes that, with significant, but not major, qualifications, belief in God or any of his competitors can be compatible with membership of the Society of HumanKind. The reason is that the ultimate uncertainty of human knowledge generated by an acceptance of the Axioms must extend to the beliefs and opinions of the Society itself. Insofar as the Society is concerned therefore, all beliefs, including its own, are equally uncertain. Some may be more coherent or defensible than others, but none is 'better' or 'worse', more 'true' or 'false', than any other. The focus of the Society, and its primary concern, is with the actions of its members and others not with their beliefs. Provided their aspirations, ambitions, actions and decisions are aimed and intended to discharge the Aim, Duty and Responsibility of the Society, their private opinions remain their own business. Including any private opinions they may have about the possibility of the existence of God.

    Fundamentalists, whether members of the Society or not, should however, take careful note of the clear distinction the Society draws between beliefs and actions in these matters. Tolerance of sincerely held belief is an unshakeable principle of the Society. But that tolerance cannot, and does not, extend to behaviour, actions or decisions that threaten the maintenance of the Conditions of its Dogma ; that is, which put at risk either the infinite survival of our species, or the conditions which permit continuous growth in human knowledge. In defence of the peace and stability of our society on which the survival of our species depends, and of our freedom to pursue knowledge, the Society puts no limit on the range or scope of its necessary response, as the Treatise on Justice makes explicit.