"Islam is a monotheistic religion that affirms the existence of One absolute and perfect God. As it spread by conquest in the 7th century, Islam encountered many new and foreign traditions, including the work of Aristotle. This repeatedly raised a vital question: were non-Islamic ideas to be considered part of the One Truth? In the 9th century, al-Kindi affirmed that philosophy and religion are merely different methods of pursuing the One Truth. Similarly (but more specifically), al-Farabi said that logic is the universal law of regulated thought, while revealed religion expresses truth in the symbols of a particular place and culture. In the 11th century, ibn Sina (Avicenna) solidified Aristotle's importance in the Islamic world and said that philosophy is the only source of knowledge -- and knowledge is the source of salvation. Avicenna said we begin with what we know, and proceed through a hierarchy of sciences toward what we don't know, culminating in "First Philosophy." Avicenna famously distinguished between essence and existence. This led to the philosophical concept of Necessary Existence (i.e. God). Avicenna said happiness is found not in sense perception, but in objects of the intellect; salvation involves correct habits of the soul and a primary understanding of Being -- i.e. contemplation of the purely divine. Al-Ghazali (1058-1111) criticized Avicenna, insisting that salvation is beyond demonstrative knowledge, and can be gained only in the "immediate experience" of mysticism. Ibn Rushd, or Averroes (1126-1196), worked to restore the independence of philosophy, separating it from religion. He said that religion may guide the masses to salvation, while philosophy -- grasped only by a small elite -- produces the speculative virtues that are necessary for attaining truth and immortality of the soul."
