The following is a chapter of Islam 101:
Islamic achievements in the fields of art, literature, science, medicine, etc. in no way refute the fact that Islam is intrinsically violent. Roman and Greek civilizations produced many great achievements in these fields as well, but also cultivated powerful traditions of violence.
While giving the world the brilliance of Virgil and Horace, Rome was also a home to gladiatorial combat, the slaughter of Christians, and, at times, rampant militarism.
Furthermore, the achievements of Islamic civilization are pretty modest given its 1300 year history when compared to Western, Hindu, or Confucian civilizations. Many Islamic achievements were in fact the result of non-Muslims living within the Islamic Empire or of recent converts to Islam.
One of the greatest Islamic thinkers, Averroes, ran afoul of Islamic orthodoxy through his study of non-Islamic (Greek) philosophy and his preference for Western modes of thought. Once the dhimmi populations of the Islamic Empire dwindled toward the middle of the second millennium AD, Islam began its social and cultural "decline."
Islam 101 was written by Gregory M. Davis, author of Religion of Peace?: Islam's War Against the World, and the producer/director of Islam: What the West Needs to Know.