Volume I of The Knowledge of God and Its Historical Development focuses overwhelmingly on the nature and historical expression of God’s revelation. After initially arguing that theism is the most plausible interpretation of the uniformities, interrelations and causations in nature, Gwatkin sets about defining the nature of revelation and mankind’s attempts to interpret it. He argues that since natural theology deduces God is a ‘Person’, it is probable for humankind to expect relationship and revelation. For the author, all revelation is from God and ‘requires action in the moral and supernatural order of persons’. By its very nature revelation must be moral and practical.

According to Gwatkin, religious movements represent humanity’s attempts to interpret revelation while maintaining a balance between the sovereignty of God and the freedom of humankind. Failures to maintain this equilibrium resulted in the ‘twin errors of Pantheism’ and ‘Deism’. Yet without falling into such extreme errors, failure to continually receive and interpret revelation can result in the stagnation of a movement. Some religious traditions become either bogged down by unbending dogma or limited in their ability to receive further revelation by strict religious laws. Gwatkin points out the propensity of many Christian denominations to become overly dogmatic, while claiming that Judaism and Islam’s strict religious codes stifle their ability to receive additional revelation, thus impeding further evolution. In contrast, he contends that ‘gospel’ Christianity possesses historical precedents but still allows for reinterpretation of historic facts and continued ‘evolutionary’ progression as it is not bound by ‘codes of law’. Finally, he states that morality must be an integral aspect in discerning the truth of revelation.

The final portion of the first volume comprises the first three lectures of the second series. Gwatkin identifies primitive religions as being the preliminary ‘childlike’ states of religious interpretation, based on fear, which represent the beginning of a continuing evolutionary process. In three short chapters he charts the shift from totemism and pantheism to polytheism and the anthropomorphism of the deity. Gwatkins argues that the great contribution of Greek philosophers came with the Stoics and their belief in the immanence of the divine in the world.