Previously on "YHWH's Excellent Adventure"
Part 1: Thus Spoke Zarathustra. In which we learn that YHWH wasn't the first god to want to be alone.
Part 2: YHWH rules, Chemosh drools! In which we learn most of Biblical history was pulled out of King Josiah's backside.
Part 3: By the Rivers of Babylon. In which the Hebrews crib most of their afterlife from the Persians.
Part 4: Alex the Kid in Hellenic World. In which Alexander the Great conquers the known world and everyone learns to love, Greek-style.
Interlude: Danny Boy, the Lions, the Lions are calling. In which Daniel becomes a Prophet despite not knowing the first things about his own surroundings.
Part 5: I ♥ MACCABEES. In which the flame of cosmopolitan Hellenism is snuffed out by religious fundamentalists.
Part 6: Quacks, Kooks and Loons of the Roman Empire. In which we see that the early Roman Empire was a utopia for two bit religious frauds and crazy cults.
Part 7: Would the real Messiah Please Stand Up? - In which we began to example just how much we really know about Jesus.
Part 8: The Greatest Story Ever Made Up - In which we see as the four gospels progressively transform Jesus from Jewish messiah and adopted son of god into the ever-co-eternal Logos and saviour of mankind
Part 9: Speaking in Tongues - In which early Christianity is finally torn from its Jewish roots, and gentiles steer the religion to a far different future than its founders intended.
Part 10: I, Constantine - In which Christianity is Romanized, and becomes the state religion of one of the greatest powers of the world.
Part 11: You say homoousios, I say Homoiousios - Christians agree to disagree, then disagree to that, and start fighting each other.
Up next...
Part 12: Rock the Kaaba!
As Christianity grew, spreading over Europe and the Near East, it suffered overstretch, and went through schism after schism. The Catholic/Orthodox centers of Rome and Constantinople made various attempts to crack down on heresy, but the religion was becoming far too widespread to control effectively, and with much of the West in the hands of Arian barbarian kings, any attempt would likely have limited effect anyway.
It was in this period, in the last decades of the sixth century AD, where the next stage of monotheism's story takes place, centered around an illiterate Arab allegedly receiving a heavenly visitation in some cave.

Above: Now listen carefully Mohammed, I'm only saying this once. And don't let me catch you putting any of that stuff about rubbing dirt in orifices in there, you hear? Also...WHAT THE FUCK IS THIS ON MY ARMS?
Yes, Mr "Camera-Shy" Mohammed himself.
According to the Qu'ran and Islamic tradition, Mohammed is the final and most accurate messenger of God, and received the direct divine revelation from the lips of the angel Gabriel (according to the Hadith, Gab has 600 wings). There's much to doubt about this story, particularly since the first few hundred years of Islamic history seems to be entirely fabricated, but we'll get to that later.
The words of Gabriel (and hence God) are allegedly reproduced word for word in the Qu'ran, but when one reads it without a lifetime of religious reinforcement of its "poetic perfection", you are struck by a few things.
One, it's an incredibly tedious work. If God's main motivation was to bore his creation senseless then, mission accomplished. Secondly, it's one of the most plagiarized works since Christopher Paolini first set pen to paper. It seems to read as a compilation of bits and pieces of earlier religions (namely Judaism, Christianity, Zoroastrianism and Arab paganism) stitched together and edited by someone who managed to completely miss the point of the original source material.

Above: Kind of like this, in fact.
In addition, given the scorn most devout Muslims have for anything that smacks of paganism or idol worship, it is perhaps surprising to see how much of old Arab paganism remains in Islam - the pilgrimage to Mecca is a blatant example, and the fact that no Muslim finds it strange that when they pray they face a magic rock stored in a big black box. Precisely how is that not idol-worship? Not to mention the absurd status afforded to the Qu'ran itself.
As for the book's content, there's nothing original about it - those pieces which aren't a heavily reworked piece of plagiarism are copied outright from other sources. Even the most fundamentalist Muslim acknowledges this, but they believe that the Qu'ran, and by extension Islam, is the final, most true version of God's word and the texts of Jews and Christians imperfect altered copies. Unfortunately for them, quite a bit of the work betrays its flaws blatantly, particularly some of the sloppy historical and theological errors.
For one, there's the figure of the "Two Horned Lord", aka Alexander the Great, who is described a pious Muslim who lived to an old age, rather than the pagan Greek who died before the age of forty. You might notice the recast Jewish and Christian prophets, suddenly spouting incredibly anachronistic Muslim theology centuries before the birth of Mohammed. Particularly ridiculous is Jesus - not described as the son of God, but as the son of a virgin nevertheless. As you may realise from earlier installments of this series, the virgin birth came about as dogma as a consequence of the insisted divine origin of Jesus - here it serves no real purpose, and is merely an unintended legacy from the Christian documents that the Qu'ran was largely derived from.
Then there's the son of Abraham, who has changed from Isaac in the Jewish/Christian story, to Ishmael, Isaac's illegitimate half-brother. The reason for this change is not immediately obvious, until you read further and notice that the Qu'ran obviously intends its audience to be Arab, and male, hence oblique references to how a reader should treat females and non-Arabs. The substitution of Ishmael, the mythical progenitor of the Arab people, casts Arabs themselves in the role of Hebrews as God's favoured people.
And that, in the end, is one of the most salient points about the religion. All faiths involve some level of political entanglements, but Islam takes that to another level. So whereas Judaism is an insular, ethno-religious cultural suit, and Christianity an evolved quasi-socialistic apocalyptic cult, Islam is, for all intents and purposes, a political movement masquerading as religion.
The folding of Arabic language, culture, and social mores into the religion proved devastating for almost every native culture that Muslim conquerors took over, from the Greco-Syriac cultures of the Levant to the many thousand year old native Egyptian culture, which even Rome wasn't able to extinguish. Muslim apologists (and the Qu'ran and Hadiths for that matter) like to claim that Islam changed the Arabs from a decadent, corrupt people, to spiritually upright and noble ones, but there's little evidence that anything changed in traditional Arab culture, except for a steady erosion in the power of women and non-Muslims.
Such aggressive cultural conquest was facilitated in newly conquered territories by the construction of garrison towns that would slowly draw on the wealth and resources of the subjugated people like some sort of colossal parasite (Cairo and Baghdad both began as such cities), and was reinforced by the punitive measures intended to sustain the power of the Muslim Arabic-speaking elite. The ridiculous idolization of the Arabic language (it being the only one a "true" Qu'ran can be written in) results from this enforced cultural supremacy, and so, even today, when the vast majority of Muslims are not Arabic nor speak the language, so Arabic cultural and social mores are foisted on them as being "part and parcel of the religion".

Above: The Qu'ran says nothing about this nonsense. But I doubt this woman or her husband know that.
Most of the truly bizarre, unpleasant, and awful aspects don't come from the holy book at all, but from a series of oral traditions known as the Hadith...and that's where we will be heading next time.