Part one is a general history of Islamic theology, exegesis, law, and mystical traditions, highlighting elements that were to be influential in Southeast Asia: the Mu'tazila and the "reason versus revelation" debate, the exegetical works of al-Baghawi and the Tafsir al-Jalalayn, mystics such as al-Hallaj (executed in 922 for teaching that believers could achieve a measure of union with the divine) and Ibn al-'Arabi, and Sufism. It also covers 20th century reformism and revolution, with a typology of Islamic responses to the modern world and a look at some of the most important figures. This provides enough background for a reader with no familiarity with Islam to follow the rest of Islam and the Malay-Indonesian World (the reader is, however, assumed to have at least a basic knowledge of general Malay and Indonesian history).
The earliest Islamic religious scholars from the region about whom anything substantial is known are four Sufis from the mid-16th through 17th century Sultanate of Aceh. Hamzah Fansuri and Shams al-Din al-Sumatrani espoused monistic doctrines, for which they were later attacked, aggressively by Nur al-Din al-Raniri (who had their books burnt) and more moderately by 'Abd al-Ra`uf al-Singkili. Malay exegetical activity showed a preference for story-telling, narrative approaches such as those of al-Khazin's Lubab al-Ta'wil (not so popular in the Arab world) and the Jalalayn ("arguably the most important work of Qur'anic exegesis in the archipelago in terms of its past and present contribution to the spread of Islam in the region"); key exegetical texts are the 16th century Cambridge Malay commentary and the c. 1675 Tarjuman al-Mustafid. The 18th and 19th centuries saw the consolidation of Sufi Islam, notably in Java, and of links to Arabia, notably by al-Nawawi and thinkers from the Patani area.
Part three offers a long survey of 20th century Islamic thinkers. This includes a couple of representatives of modern Sufism and "orthodox traditionalism", but the vast majority of the voices have been "modernising". Among those are high profile figures such as Anwar Ibrahim, Abdurrahman Wahid, and Amien Rais, but it is their religious ideas that are of interest to Riddell, not their politics. Similarly, organisations such as Muhammadiya and Nahdatul Ulama and political parties such as PAS are mentioned only incidentally. Riddell explains the absence of neo-normative revivalists ("fundamentalists"): they "have never exerted anything other than marginal influence on the direction of events in Muslim Southeast Asia this century". Separate chapters cover the revival of exegesis after a fallow period of several centuries, focusing on Hamka and Ash-Shiddieqy, and themes in recent popular preaching, in both print and electronic media.