The Hidden Origins of Islam: New Research into Its Early History by Karl-Heinz Ohlig and Gerd-R Puin (Jul 30, 2009), available at Amazon.
The standard histories of Muhammad and the early development of Islam are based on Islamic literature that dates to the ninth and tenth centuries–some two centuries or more after the death of Muhammad in 632. Islamic literary sources do not exist for the seventh and eighth centuries, when, according to tradition, Muhammad and his immediate followers lived. All that is preserved from this time period are a few commemorative building inscriptions and assorted coins.
Based on the premise that reliable history can only be written on the basis of sources that are contemporary with the events described, the contributors to this in-depth investigation present research that reveals the obscure origins of Islam in a completely new light. As the authors meticulously show, the name “Muhammad” first appears on coins in Syria bearing Christian iconography. In this context the name is used as an honorific meaning “revered” or “praiseworthy” and can only refer to Jesus Christ, as Christianity was the predominant religion of the area at this time. This same reference exists in the building inscription of the Dome of the Rock in Jerusalem, built by the caliph `Abd al-Malik.
The implication of these and other findings here presented is that the early Arab rulers adhered to a sect of Christianity. Indeed, evidence from the Koran, finalized at a much later time, shows that its central theological tenets were influenced by a pre-Nicean, Syrian Christianity. Linguistic analysis also indicates that Aramaic, the common language throughout the Near East for many centuries and the language of Syrian Christianity, significantly influenced the Arabic script and vocabulary used in the Koran. Finally, it was not until the end of the eighth and ninth centuries that Islam formed as a separate religion, and the Koran underwent a period of historical development of at least 200 years.
(Source: Amazon description of ‘The hidden origin of islam’ by Ohlig, Puin et. al)