The first chapter provides a broad overview of an approach to a natural theology derived from the study of comparative religions, which Zaehner makes the topic of his study. Zaehner pays special attention to the Second Vatican Council’s statements on non-Christian faiths, pointing out the areas in which the underlying beliefs and assumptions of Hinduism, Buddhism and Islam both do and do not appear to be compatible with those of Christianity. The second chapter then traces the shifts between law and mysticism in world religions, providing something of a broad overview of the shape the argument will take.

The third chapter focuses more seriously on mysticism or, as Zaehner puts it, ‘cosmic consciousness’, moving from a discussion of the effects of mind-altering drugs to a comparison between the poetry of Walt Whitman and Hindu mysticism. The fourth chapter explores spirit/matter dualism and the transmigration of souls, focusing especially on the Rig-Veda and the Upanishads. The fifth chapter continues the analysis of the Upanishads and their portrayal of the ‘unity in diversity and diversity in unity’ which characterises the Hindu concept of the Divine and the self. The sixth chapter then focuses on the emergence of a personal God in the Hindu tradition and on the incarnations of Shiva. The textual focus of the chapter moves from the Upanishads to the Bhagavad-Gita.

The seventh chapter moves from incarnation to transcendence and compares the Gita to Buddhist philosophies and yoga. The eighth chapter then considers the Bhagavad-Gita as the bridge between Eastern and Western mysticism. The ninth chapter engages in a reading of the Gita’s central conflict between Yudhishthira and Krishna, with attention once again given to Buddhist philosophies. Finally, the tenth chapter reviews and details the varieties of mysticism which have been uncovered in the preceding lectures: the transcendence of spatial limitation, the transcending of temporal limitations, the transcendence of both space and time into pure being and the transcendence of being itself.

The second series of lectures begins with the eleventh chapter, ‘The Way of Heaven and Earth’, which turns to consideration of Taoism and Confucianism. Unlike the Hindu and Buddhist drives toward transcendence, Zaehner argues, Taoism and Confucianism strive toward a return to a state of natural innocence and unity with all things. The twelfth chapter investigates the Confucian and Taoist concepts of humankind's place in relation to the rest of the universe, primarily by way of comparison to Buddhism. The thirteenth chapter focuses on approaches to synthesis between paired opposites (male and female, heaven and earth) in Confucian and Taoist thought, with references back to the conflict between Yudhishthira and Krishna.

Chapter 14 introduces Zen as an alternative philosophy which emerged from dialogue between Buddhism and the declining neo-Confucianism. Emphasis is given to the Christian notion of the union of soul and the Divine as it relates to the Zen idea of oneness with nature. Chapter 15 then expands on mysticism within the Christian tradition, with special reference to Hugh and Richard of St Victor. Chapter 16 explores the dark side of mysticism, from St Theresa's warnings about demonic deception to instances of mass hysteria. Zaehner observes that Judaism is peculiar in its avoidance of any truly mystical tradition.

Chapter 17 focuses on Jung’s approach to religion with particular reference to Answer to Job, and then shifts from Job specifically to the problem of suffering in general, answering it with mystical incarnation in the person of first the Buddha and then Jesus Christ. Chapter 18 moves from the Christian doctrine of the Incarnation to a discussion of the Church.

Chapter 19 returns to the theme of dualism, exploring myths of cosmic warfare and their contemporary analogues, with specific mention given to Marx and The Brothers Karamazov. Finally, chapter 20 focuses on spirit-matter dualism and Christian attempts at synthesis, particularly through the work of Teilhard de Chardin.