No.

For a more detailed answer, see this similar question posted last month: http://www.reddit.com/r/AskHistorians/comments/1t03qi/before_he_founded_islam_what_religion_did/

Tack-On Question:

Where would Zoroastrianism have been the dominant religion in AD 500, besides modern-day Iran?

You may be interested in the 'What was the religion in the Arab world before Islam?' section of the Popular Questions pages.