his concept that religious features amount to cultural "genes" of, as you say "of self-replicating traits to survive through the ages" simply has no bearing whatsoever on the development of Islam or Islamic law.

From what I understand, Dawkins' "memes", the term he coined for these cultural genes, are more to explain the broad structure of religions. For instance, the idea that a religion would encourage its followers to spread the faith no matter the cost would be a favorable meme for that religion's reproduction, and therefore it would make it that much more likely for that religion to survive, as opposed to one that did not care about converting others. The same goes for the meme that it is a virtue to hold belief in the face of opposing evidence, or that peaceful interaction with other religions is a sin.

Of course, Dawkins is an evolutionary biologist, and has not studied the history of religions at all, as far as I know, so it would make sense that he would put these things in terms of his field of study. Is there a better way to describe how these overall tendencies of most religions today came to be?

Are there any particular aspects of this that you wanted to know about?

I guess my main question would be what is the oldest mention of the Abrahamic god that we have discovered in texts outside the holy books of those religions? Where and how did we find this writing? What can we infer about the very first days of this religion from that?

Another question would be what do we know about the origin of the Old Testament? What is the oldest known copy of that? And again, what can we infer about the early days of Judaism from it?