User blog comment:LurkerLordB/Religion in a world without Christianity/@comment-1777104-20120424214749

I have to conclude that Islam would indeed rise up, for it is an extension not of Christianity but of its arch rival Judaism. They are 'cousins' as it were. Mohammed was influenced by the pagan religions that were found in his part of the world, and is said to have been visited by an angel (much like those found in the scriptures of the Jews). The rise of Islam was a return to the religion of Abraham through the line of Ishmael, his first born. With Muhammed monotheism returned and much of what became law under Moses (said to be a prophet by Islam) became Islamic Law as well.

Without Christianity to defend them, Jews would not have fared well against the Muslim invasion of Palestine and surrounding areas, but it is doubtful the Jews would have returned there in modern days any way. Being monotheistic, and miltiantly so, Islam would have prevailed over many polytheistic societies. Its fervor for the sciences early on would have contributed to a renaissance in Europe after the 'dark ages' that would have occurred with the sack of Rome and its surviving society. I figure that sense Rome borrowed its religion from Greece, the pagan deities would be interchangable, but I might be wrong.

Without a solidifying religion, it is doubtful that the Iberian Peninsular woud have withstood the Muslim advance into Europe. It is hard to tell how far they would have advanced, but I'm thinking it would have been at least to the Pyranees. With control of the Strait of Gibralta and the Red Sea, the Muslim world would control trade by sea and probably take over control of the Mediterranean as well. If Spain and Portugal became the sea powers that they became, the New World would be discovered and claimed by the Muslims as well.

The Celtic religions of the British Islands, meanwhile, would be mostly over-run by the Nordic peoples and their religions. None of these being particularly evangelistic, the groups may have continued together and over time even become intertwined. Being related as they are to the Nordic religions, though, it is tempting to think the combined peoples might have followed the Vikings in their journey to the west via Greenland. If left to common history, though, the English would have explored North America as they did in our time line, but without any religious fervor that spurred many. Virginia would have been successful, for a time any way, and been the center of whatever would become of the continent.

Modern day Judaism would have survived through all of this, perhaps even thriving until the twentieth century. Without a Christian fascade, Hitler may not have been able to muster support for his plans -- if modern Germany would ever arise without the Church that is. As an Austrian in the Austrian-Hungarian Empire, for instance, would he even have had the opportunity? Ah the butterflies! It could be argued that Hebrew (Jewish) thought would have been the best for the advancement of science in the west. Without the holocaust, in fact, the twentieth century may have been turned into the "Jewish Century."

Eastern religions would have continued, running into Islam as they have in OTL. Without Christian missionaries from the west, Zorastrianism or some other mystery religion may have spread into northern Asia (Russia). However, Jews were dispersed into that direction as well, so their monotheism might prove popular in that direction as well.

Well that is my considerably large "two cents" worth. :-)