How did the Islamic faith begin?

The Islamic creed is the creed of all prophets and messengers, from Adam to Muhammad, peace be upon them, because their religion is one, even if their laws differed. This is in accordance with the Almighty's saying: ﴿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.﴾ [Al 'Imran: 85]. Deviation afflicted the followers of previous religions, so Allah sent messengers to correct this deviation, until Muhammad, peace be upon him, came. And Allah preserved His religion from distortion and alteration, in accordance with the Almighty's saying: ﴿Indeed, We have sent down the Dhikr, and indeed, We will be its guardian.﴾ [Al-Hijr: 9]. And the Ummah of Muhammad is infallible from agreeing upon error, and a group of them will remain upon the truth. As for the beginning of the fixed truths in this creed, they are eternal and relate to Allah and His names and attributes. And the beginning of man's knowledge of them was with Adam, peace be upon him, who was upon this creed.