Assmann's wonderfully easy, careful writing reveals all the features of Egyptian religion a way no other book achieves. He explores religion in two terms: 'divine presence.' These terms meaning sacred (transcendent), and mundane (immanent) realms. The distinction extends Durkheim's distinction of sacred and profane, because divinity was present in the world for the Egyptians. 'Divine presence' for the Egyptians meant realizing plenty (ma'at) over against lack (isfet) both in the divine order by pacifying the gods and in the mundane order by instituting ethical conduct. He studies the 'narrow view' of religion: pacifying the gods. He leaves the wide view - ethical conduct - aside a task of sociology.
To arrive at the Egyptian 'narrow view,' Assmann distinguishes 'implicit theology' from 'explicit theology.' Implicit theology is his theory of how the Egyptians thought that he drives from interpreting texts. Explicit theology means whatever theory the Egyptian natives may have had, but the Egyptians 'never referred to [explicit theology] in practice.'
His 'implicit theology' is not 'reading into' the liturgies, but summarizing their consistent literary devices. An example of 'implicit theology' is the consistent progress in the ancient liturgies from names, to embodiments, to statues. Such consistent liturgies reveal civil, natural, and mythical levels of religion. Studying implicit theology in the liturgies over the 3,000 or so years of the dynastic periods reveals that polytheism played the particles to waves of monotheism.
A transition from localized polytheism to national monotheism occurred over the course of Egyptian history. During the transitions from Old to Middle to New Kingdoms, immanence in local cults of city gods transmuted to ruler god, primeval god, creator god, sun god, and to the ethical authority of personal devotion. The solar cult of the Amarna period, so often portrayed as Enlightenment, was a conservative repression that persecuted any personal experiences of the older religions of Ammon by interposing the royal couple between the Aten and people. The unexpected consequences of the persecution was the 'breakthrough' to the 'fourth dimension' of personal ethical consciousness, the same general development that describes the 'axial age,' the appearance everywhere of the historic religions at the end of the ancient world. Assmann's communicates the consistent beauty of the major hieroglyphic liturgies by demonstrating the logic of the litanies. Egyptian 'polytheism' was simply the symbolization of transcendence in immanence -- all the 'forms' (cheperu) of immanent experience are manifestations of searching for transcendent God. 'Search' in this context does not mean conscious theologizing.