you crafty monkey, Roy! Having a peek on my website, eh?!
My interest in Islam - and my entering 'the fold', so to speak - was because I found out about the Sufis (whom I mentioned earlier) who try to live by the meaning of the Qur'an. After 2 or 3 years theoretical reading, I then became and remained a formal Muslim for around 7 years and came to get my knowledge about all the main sects as a result. Since then (since ca. 1985), I went away from religious teachings, but some experiences brought me back, but this time to learn about the Gnostics of early Christianity and Vedanta (the basis of Buddhism and the Hindu faith).
In response to your question about "a different book" in Islam. To answer that I have to elaborate a bit more on the difference between the Sunnis and the Shia.
All Muslims profess belief in Allah, Prophet Muhammed and the Qur'an. Therefore they all take the Qur'an as being the central book. HOWEVER, the
Sunnis have always preferred the external practises of Islam and they take their line of understanding according to 4 theologians of the Middle Ages - Hanafi, Hanbali, Shafi and Muslim - who expounded the
external faith of Islam according to the practises of the Prophet - how he prayed, ate, greeted people etc. etc. The written doctrines of these theologians differ only in small details. The
Shia, on the other hand, allege that they were told by the Prophet that his son-in-law, 'Ali, was to be his heir, and that interpretation (ta'wil) of the Qur'an should come from him and his progeny. The Sunnis (the majority) did not listen to the Prophet's bequest and instead elected three other leaders (Kalifs) in succession, until 'Ali finally became leader of the Muslims. He was assassinated. And then there was the slaughter at Kerbala that I spoke of earlier.
So the main difference between Sunnis and Shia is that although they all accept the Qur'an, the Sunnis go by the words of the theologians who laid down what they understood to be the practises of the Prophet, and the Shia go by the word of the prophet's son-in-law ('Ali) and his progeny, who are supposed to interpret the Qur'an
according to the times. The Isma'ili Shias, who have the Aga Khan as their leader, are the only group of Shia who follow a living descendant of 'Ali, and he interprets the Qur'an according to the times, as was intended (according to the Shia). The Shia of Iran and Iraq still follow doctrines laid down by the last of their leaders, who disappeared hundreds of years ago, and who are therefore still rooted in the Middle Ages, as are the Sunnis.
Effectively, only the Sufis and the Ismai'li Shias have an accurate understanding of Islam, as I understand it. There are imams (religious leaders) of the Sunnis who are reasonable.