There are many introductions to Christian theology, and I will not try to add to them here. A word may be needed about Islamic theology, concentrating on its formative period (750-950).

The five chapters listed in the table of contents are the main issues, in the order of their historical emergence, which dominated Islamic theological debate in the period under consideration. These debates either arose from or had serious implications for the political situation of the time. To understand them, I present here a résumé of my Early Islam, chapter 15.

The first issue, the relationship between faith and practice, arose directly from the chaos in the Islamic world following the assassination of ‘Uthmân. Muslims are supposed to be at peace with one another (Q 3:103; 9:71) and to fight only unbelievers (Q 9:123 etc.) The three-way civil war between Mu’âwiya, ‘Alî and the Khârijites could be justified only by supposing that the enemy was an apostate, since by his behaviour he had forfeited the right to call himself a Muslim. The Khârijites formulated this position and applied it to all besides themselves who claimed to be Muslims.

During the Umayyad period a party was developing based on loyalty to the family of ‘Alî. It took some time, until the ‘Abbâsid period, for this party to take shape and adopt the name “Shî’ite”. Also during the Umayyad period Qur’ânic studies made much progress, laying the base for its paramount authority in what was later to become Sunnism.

The Umayyads utilized religious ideas to enhance their own authority, giving rise to the second debate. The pre-Islamic idea of destiny (qadar), remoulded in the Qur’ân, was used to support their authority as decreed by God, forcing their opponents to argue for the role of free human choice.

As the Umayyads consolidated their authority, a mainstream unity developed in the Muslim community, leaving on the sidelines the Shî’ite exaltation of ‘Alî (especially in Kûfa) and the Khârijite condemnation of everyone who did not measure up to their own behaviour expectations. Abû-anîfa was the principal formulator of the teaching which came to be known as Murji’ism. This is that Muslims should leave the judgement of the case between ‘Uthmân and ‘Alî to God. In the meantime anyone who outwardly professes Islam should be accepted as a Muslim, and rulers in power should be presumed to be legitimate. This was the Sunnite resolution of the first debate.

As for the third debate, the ‘Abbâsid period saw the growth and reformulation of Shî’ism, although always as an opposition movement or at times as a junior collaborator in government. Radical Shî’ism made no compromise on the primacy of ‘Alî and his rightful heirs, although there was no unanimity which these were. The caliph al-Ma’mûn patronized a compromising group of Zaydite Shî’ites who recognized the superiority of ‘Alî and his line, but were prepared to accept a less deserving ruler who could be elected. Shî’ism eventually divided into two main branches, the Ismâ’îlîs, or “Seveners”, who recognize a line of seven imâms before the line went into hiding, and the Imâmites, or “Twelvers”, who recognize twelve imâms before the line went into hiding.

The ‘Abbâsid period also saw a large scale introduction of Greek philosophy and science into the Muslim world, occasioning the fourth debate: What is the relationship between revelation and reason? Discussions between Muslims and Christians and between different Muslim schools of thought led to the application of philosophical concepts to talk about God, giving rise to the fifth issue: What is the relationship between God’s substance and his attributes and between one attribute and another? Both questions were taken up by the Mu’tazilites and their break-away cousins, the Ash’arites.