The closest equivalent to “theology” in Arabic is kalām. It is not an exact translation, however, so we must begin by defining what is meant by “Muslim theology”. Provisionally, this can be done negatively by distinguishing it from terms which do not designate Muslim theology and which are the subjects of other chapters of this book.

Theology is not fiqh, Muslim jurisprudence; nor, even in its juridical capacity, is it the sharīʿab, revealed law. The sunnah must be excluded too because, as an oral tradition, it is revealed, like the sharīʿab, and constitutes the source of theology, therefore, rather than theology itself. In Christianity, mysticism is a branch of theology, but in Islam not only does it fall outside the domain of theology, in the general sense in which Muslim theology is understood, but is even regarded with some suspicion by the more traditional elements. Besides which, mysticism's unique nature calls for a singularly non-rationalist methodological approach. The term millah is synonymous with “religion” as man's expression of divine revelation, or of his relationship with the Deity, and, therefore, comes no closer to conveying the sense of the word “theology”. Nor should this be confused with falsa/ah, Muslim philosophy, although arguably their content is the same, for, whereas the starting-point of philosophy in Islam is reason, that of theology is revealed faith. Yet, while Muslim theology cannot be equated with any single one of these subjects, it is rooted more or less directly in all of them.