I guess I've sort of taken for granted that Christianity, Judaism, and Islam are the "Abrahamic faiths." Recently, though, out of curiosity, I decided to sit down and read the Koran, and as I sat there scanning through the Adam and Eve story, or reading something about Moses, it struck me that I had no idea how these common elements of belief ended up in Arabia anyway--how did this guy in 7th century Arabia, who wasn't a Jew, come to believe this stuff?
Certainly, I know enough to know that Islam didn't grow out of Judaism as, say, Christianity did, but evidently, pre-Islamic Arabs shared a lot with them. How much do we know about Pre-Islamic Arabian religion? Is there some specific name for the religion that Mohammed was born into? In addition to the populations of outright Christians and Jews there, were there particular groups that were more "Abrahamic" and those that were more "pagan?" I know that a lot of Islamic religious practice had something to do with what was already there--the locals had been performing rites around the Ka'aba, albeit very different ones, for instance, but how "Abrahamic" were those folks? How and when did Abrahamic beliefs get to the area?
You may also be interested in reading some of the answers in this fairly recent AMA on Pre-Islamic Arabia.
Pre-Islamic Arabia was a mix of a few religions at this time. The main religions in this region were Judaism, Christianity, and a form of Pagan tribal religion. While there is some evidence to suggest that some of the Pagan people believed that there was only one God, most believed in multiple deities and had a personal/family deity that that individually worshipped. Overall the Pagan people were non-Abrahamic and polytheistic. Other traits of theirs would be incorporated into Islam but not their polytheistic traditions.
When you examine early Islam it is important to remember that Muhammed saw himself as worshipping the same God as Jews and Christians but that they had gone astray and God talked to him to show these people how they had gone astray. The reason why you see many similarities with Judaism and Christianity is that Islam believes that these religions were founded by the same God that talked to Muhammed.
I asked a very similar question recently, that received some informative responses.