This research tests C.G. Jung’s suggestion that if protestant Christians think of God as a mythologem then it advances consciousness. There is an implied benefit of greater religious tolerance. The research methodology is to investigate the theoretical concepts involved, operationalise them, and then conduct an empirical test of their relationship. There are multiple problems that have to be overcome, including Jung’s amorphous and protean use of terminology. His concept of myth, in this context, is clarified and positioned within his philosophy, (...) the contemporary culture of materialism, and the primary beliefs of the target audience. The contemporary understanding of Jungian consciousness is also revisioned to incorporate Jung’s notion of advancement based on the transcendent function. There are no existing measures for ‘thinking mythologically’ nor ‘advancement’. The concepts do not lend themselves to established psychometric principles. Therefore, two new forms of questionnaire are devised to measure these concepts, alongside two new questionnaires of conventional design that collect information about demographics and religious tolerance. There is an Information Technology sub-project, using a bespoke database and set of programs, to develop, publish, and promote the questionnaires on the internet. There are then two stages of statistical analysis: one to develop reliable and valid measures for each concept; the other to measure the relationships between the concepts. The main result of the test is that the specific relationship Jung describes in the letter – between mythological thinking and advancement of consciousness – does not hold. However, the data does suggest there may be a direct relationship between mythological thinking and religious tolerance. Despite the failure of the main test, there are a number of useful lessons from the results and suggestions for future research. There are also several spin-offs from the thesis, in terms of both concepts and resources. These are reviewed in the final chapter. (shrink)