The beginning of the religion of Islam
27-6-2007 | IslamWeb
Question:
When was the date that the religion of Islam started ?
Answer:
All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad 
is His slave and Messenger.
The history of the religion of Islam goes back to Aadam 
and all the Prophets and Messengers from the time of Aadam to the last Prophet and Messenger Muhammad practised the religion of Islam as we clarified in Fatwa 88906, so please refer to it. No Prophet or Messenger even practised a religion other than Islam even though some of their legislations might have differed. Additionally, Allaah does not accept any religion other than Islam; Allaah Says (what means): {Indeed, the religion in the sight of Allaah is Islam.}[Quran 3:19]. Allaah also Says (what means): {And whoever desires other than Islam as religion – never will it be accepted from him, and he, in the Hereafter, will be among the losers.}[Quran 3:85].
For more benefit, please refer to Fatwa ">85767.
Allaah Knows best.