Let there be no clash of religions.
First of all Jesus Christ Was not a Christian. He was a rabbi who followed the Mosaic law to the “dot and tittle” and preached that the Mosaic law must be followed in the minutest detail and whoever forgoes the smallest of the Commandments of the law and tells others to do so will be considered the least in the kingdom of heaven ( Matt. 5:15-19. Yet Christians ( in practice followers of Paul ) have decided to set aside this basic and most explicit of their “ Lord ”’s commandments, and set themselves free of all the constraints of Mosaic law in favor of Galatians 3:13. Thus, they in fact declare, ( in support of the Pagan Greco Roman creed), “ My / our Kingdom is of this world alone”, where is there supposed Lord had proclaimed my kingdom is not of this world”. The original message of Jesus Christ ( pbuh ) ( still largely unknown since no authentic Aramaic Gospels have ever been unearthed ), was almost completely manhandled and disfigured in the following centuries by the so-called earlier self claimed followers of Jesus ( pbuh ) thus fulfilling Matthew 15:9 perfectly. It took the message of Quran ( it calls it’s followers as “ the middle ( moderate ) nation “ ) six centuries later to declare “ Our Lord, bestow upon us the good of this world and the good in the life to come ( Q 2:201 ).
Almost nothing is left of the message of the Jewish Messiah. The whole Law ( the cornerstone of ALL Hebrew prophets ) has been thrown out ignominiously as “ irrelevant”. All religious festivals of the Christian world are openly pagan festivities. December 25 happened to be the birthday of Roman Sun god. Decorated Christmas tree, the universal symbol of this coming upcoming holiday season, is condemned as a pagan practice by Jeremiah ( 10:2-5 ). Easter is the pagan Roman Holiday of goddess Esther with its fertility symbols of eggs and rabbits. Paul himself declared that in order to win men to Jesus he really did not have a consistent message ( my paraphrase of 1 st Corinthians 9:19-23 ). Of all the “ civilizations “ “ you have mentioned making up western civilization, Jesus’s message constitutes a tiny percentage. His message was that of Moses; strict unambiguous Unity of Godhead and the Law with its 613 commandments.
By the way Spengler theorized that various civilizations developed independently. He lumps together Jewish, Christian, Islamic and Zoroastrian civilizations as “ Magian” civilization. I do not agree with this premise of his but I believe his labeling of the current western civilization as the “‘Faustian Civilization” is totally correct. I see hardly any true “ God consciousness “ in the average Joe / Jane. No desire “to walk the talk “to conclude this post.