Just want to mention that Arabia had a very substantial Christian community, especially and not surprisingly in the cities of the coastal regions, right around the peninsula. However, Christianity never suceeded to penetrate the interior of Arabia, the Beduins remained pagan. Unfortunately, I do not know anything about the character of their religion.
But not only that, in the 6th century, the King of, what today is Yemen converted to Judaism, starting a presecution of Christians, which caused the Ethiopian King Kaleb of Axumite Empire, by then already christianised, to invade Yemen and put a Christian king on the throne, whose successors survived under Ethiopian protection for a few decades.
The advance of the Sassanid Empire into Arabia at the end of the 6th century, again around the Eastern and Southern coastal regions, introduced their state religion, Zoroastrianism
For the development of Islam, the Christian and Jewish traditions in Arabia were certainly more influential than those of the pagan nomad tribes.
Edited by Komnenos - 23-Aug-2006 at 17:27