Hagarism begins with the premise that Western historical scholarship on the beginnings of Islam should be based on contemporary historical, archaeological and philological data, as is done for the study of Judaism and Christianity, rather than Islamic traditions and later Arabic writings. The tradition expresses dogma, and tells historically irreconcilable and anachronistic accounts of the community’s past. By relying on contemporary historical, archaeological and philological evidence, the authors attempt to reconstruct and present what they argue is a more historically accurate account of Islam’s origins.
According to the authors, 7th century Syriac, Armenian and Hebrew sources depict the formation of Islam as a Jewish messianic movement known as Hagarism, which migrated into the Fertile Crescent. It drew considerable influences from the Samaritans and Babylonian Judaism. Around 690 AD the movement shed its Judaic identity to develop into what would later become Arab Islam. The surviving records of the period describe the followers of Muhammad as Hagarenes, because of the way Muhammad invoked the Jewish god in order to introduce an alien monotheistic faith to the Arabs.