The Origins of Human Religion - Part III
The Sources of  the Abrahamic Religions

The three Religions of the Book, Judaeism, Christianity and Islam, sometimes also called the three Semitic Religions, or the Desert Religions, are essentially three branches of the Abrahamic religion--i.e. the religion that started with a tribal chief  or patriarch called Abraham, who lived in Ur Kasdim--often rendered in English as Ur of the Chaldees--which is generally understood today as being in the location which is now called Edessa in modern Turkey--in a region traditionally referred to as northern Mesopotamia:

Ur Kaśdim - Wikipedia, the free encyclopedia

Shows the location of Edessa within modern Turkey.

This seems to be generally the location agreed on by many but not all sources:

Ur Kaśdim or Ur of the Chaldees (אור כשדים) is the town in the Hebrew Bible and related literature where Abraham was said to have been born. The traditional site of Abraham's birth is in the vicinity of Edessa although Ur Kaśdim has been popularly identified since 1927 by Sir Charles Woolley with the Sumerian city of Ur, in southern Mesopotamia, which was under the rule of the Chaldeans — although Josephus, Islamic tradition, and Jewish authorities like Maimonides all concur that Ur Kaśdim was in Northern Mesopotamia — now southeastern Turkey (identified with Urkesh, Urartu, Urfa, and Kutha respectively). 

Ancient history is rarely entirely clear or explicit and there is obviously still a still great deal of controversy about the exact location and identity of Abraham's place of birth--see for instance: Ur of the Chaldees, various proposals --as well as:  Biblical Archaeology Review May/June 2001: Where Was Abraham's Ur? --or: UrofChaldeesurfaurie , from which I will excerpt the following comments:

Scholars are divided as to Ur's location, positing it is either Urfa in modern Turkey or Ur in Babylonia, modern Tell Mughayir alternately rendered Mugheir, Mugayyar, Muqayyer, Muqqayir or Muqqayyar. This brief article investigates the claims made by both sides. Professor Sarna, favoring it to be Babylonia, notes that the term "of the Chaldees (Hebrew: Kasdim)," dates the Abrahamic narrative to no earlier than the 7th century B.C.:

"The difficulty, however, lies with the designation "Ur of the Chaldeans." The name "Chaldeans" as applied to lower Mesopotamia does not appear before the eleventh century B.C.E., many hundreds of years after the patriarchs. The city of Ur itself could not have been called "of the Chaldeans" before the foundation of the Neo-Babylonian empire in the seventh century B.C.E. The characterization therefore, as distinct from the tradition, would seem to be anachronistic." (p.98, "The Problem of Ur," Nahum M, Sarna, Understanding Genesis, Shocken Books, New York, 1966, reprinted 1970, ISBN 0-8052-0253-6)

If Professor Sarna is correct, that the term "Ur of the Chaldeans" must have arisen after the rise of the Neo-Babylonian Empire of the seventh century B.C., then Genesis and the Pentateuch was probably composed no earlier than this period.

Finally--here's a comment from a Jewish source:

 Crash Course in Jewish History #68 - Timeline: From Abraham to the ...

Jewish history doesn't happen in a vacuum. No people's history happens in a vacuum. So before we take a closer look at Abraham, we must first zoom out and get a little understanding of where Abraham fits in the world of his time.

Abram's father Terah was apparently an idol maker. In the context of those ancient times you have to think of an idol maker as akin to a maker of images or icons as in today's tele-communication devices such as telephones, computers or television sets, for idols were for their own time more or less equivalent artful,  technological devices to focus attention and energy on--or to click on so to say, for the purpose of tuning in on a certain wave length in the spectrum of the flow or spirit of energy  and thus to access a specific  site, situs or locus of  information, power or authority that dealt with certain matters, some very specialized or limited, others more broadly defined.

In other words, you could best understand the act of contemplating the face of an idol or staring into its  entrancing eyes--often made of precious stones--as a kind of tuning method for it was a way of receiving and sending communications over a long distance, like we do today when we tune in on some television channel or hook up to the internet by clicking on an icon.

The fact that we use an icon to click on when we try to access someone's  website is not accidental--it just goes to show you that focusing on an ancient idol (or icon) is not all that different from focusing on a more contemporary icon (or idol.) The technology and the belief system may have changed but the basic purpose is still very similar.  The meaning of either icon or  idol is likeness or image, interchangeably.

The practice of meditating on the face of a spiritual teacher or guru, or on the face of some saint or even on an image of the crucifix, or some other religious representation is essentially not much different than tuning into a certain kind of spiritual energy, or clicking on the appropriate icon of a more technologically contemporary telecommunications device such as a computer. 

Even contemplating the picture of a loved member of your family will bring you closer in spirit to that person--who can deny it? It is all a matter of tuning in on the flow of spiritual energy, while pin-up pictures during the Second World War often accomplished the same thing--at yet another level of consciousness. And then there is windowshopping, looking at things you could never afford but which make you feel warm and fuzzy about when you contemplate them, in the mall or in catalogues or even on some of those awful commercials or 'paid programming' stations: "Hi I'm Billy Mays! Buy this...stuff... from me because I am so fascinating!"

Other people just love to contemplate food--wonderful, glorious steaks or pastries. Or how about listening to music? American Idol? The next Model? Or sports? Doesn't that tune you into all sorts of flowing spiritual energy channels? Some people in Boston probably get all glasssy eyed when staring at a pair of  Red Socks--while in Chicago, maybe they get all silly about some White Socks. What about the stock market--does that get you excited? And there are of course the many channels of blood, gore, filth and violence that millions of people love to click on night after night. Whatever blows your skirt as an old friend of mine used to say.

Even if you disagree with me regarding what idols or icons are for, you might still be able to appreciate the metaphorical quality of the comparison. But the idea itself has been around for some time--and it is called:  Bicameralism (psychology) - Wikipedia, the free encyclopedia .

The term was coined by psychologist Julian Jaynes, who presented the idea in the 1976 book The Origin of Consciousness in the Breakdown of the Bicameral Mind, wherein he made the case that the bicameral mentality was the normal state of the human mind everywhere as recently as 3000 years ago. He used governmental bicameralism metaphorically to describe this state, where the stored up experience of the right hemisphere was transmitted to the left hemisphere via auditory hallucinations. This mental model was replaced by the conscious mode of thought, which Jaynes argues is based on metaphorical language. The idea that language is necessary for subjective consciousness or higher forms of thought has been gaining in acceptance in recent years, with proponents such as Daniel Dennett, William Calvin, Merlin Donald, John Limber, Howard Margolis, and Jose Luis Bermudez.[1]

Jahn's book, which I read in the late seventies or early eighties, is still great reading as far as I am concerned.

But maybe we should return to our main task, which was to discuss the sources, bronnen or origins (same thing) of Christianity and its many forms.

The reason I decided to start with Abraham, is because that's where Judeaism started, and hence also its off-shoots, Christianity and Islam. Prior to Abraham there were the Habiru, of which he may (or may not, some say) have been a member. Most scholars would agree that the Hebrews have their origin in these Habiru--but before Abraham they were not really an ethnic group--more a a group of bands like the Cossacks: a loosely organized paramilitary militia that moved around a great deal and engaged in both agriculture and animal husbandry:

Habiru - Wikipedia, the free encyclopedia

Carol Redmount who wrote 'Bitter Lives: Israel in and out of Egypt' in The Oxford History of the Biblical World concluded that the term "Habiru" had no common ethnic affiliations, that they spoke no common language, and that they normally led a marginal and sometimes lawless existence on the fringes of settled society.[4] She defines the various Apiru/Habiru as "a loosely defined, inferior social class composed of shifting and shifty population elements without secure ties to settled communities" who are referred to "as outlaws, mercenaries, and slaves" in ancient texts.[5]

In that vein, some modern scholars consider the Habiru to be more of a social designation than an ethnic or a tribal one. That does not, however, exclude the possibility that the Biblical Hebrews were descended from one specific group of Habiru and that with them it eventually became an ethnic name; such shifts in the meaning of names and designations are well-known elsewhere.

In any event, Abraham appears to have made a clean break with the way of his ancestors, who must have been 'idol worshippers' and for whatever reason decided to move away from the place where he was born and raised to look elsewhere for new pastures and a new homeland for the small tribe he had become the chieftain of. 

Thus the Sumerian as well as the Habiru origins of Av-ram (meaning Father Exalted) or Abraham as he became known eventually (which has no literal meaning in Hebrew but is often rendered as Father of Many (from: Av Hamon) must have entered into the origins of all three Abrahamic religions--as is clear from the many stories in the Bible we see reflected in much older versions of the same narratives that appear in Sumerian records: Biblical parallels in Sumerian literature and one particular reference in this link has to do more specifically with Jesus:

As far as the New Testament goes, many also draw a parallel between Dumuzi and Jesus because Dumuzi is a shepherd-king and he is resurrected from the dead. This is perhaps appealing to some as Dumuzi's Akkadian analog, Tammuz, appears in the Bible, however Dumuzi's periodic return from the underworld is not unique even in Sumerian literature. His sister Geshtinanna also rises from the dead, and if one counts those born as deities, Inanna does as well. Periodic death and rebirth is a common theme in agricultural myths where the return of the deities from the earth mirrors a return to life of plants.

Some of these 'Sumerian' stories may have been absorbed much later, at the time of the Babylonian exile and yet other sources of Abrahamic religion could be found in Egypt (i.e. after Abraham, but well before the Babylonian exile) and even more influences can be found in the relatively friendly, generally tolerant religion of  Zoroastrianism or Mazdeism, the official religion of the Persian rulers who allowed the Jews to return to their homeland and rebuild the temple.

Obviously after 70 years they didn't come empty handed or empty headed--I mean they brought with them many things they had learned and not the least of these were many religious concepts and ideas which eventually also crept into Christianity and Islam.  See the following link and the excerpt underneath:

ZOROASTRIANISM in the Bible Encyclopedia - ISBE (Bible History Online)

As a matter of fact, after Israel's contact with Persia the following elements, all known to Mazdeism, appear, and apparently for the first time: (1) a formal angelology, with six (or seven) archangels at the head of the developed hierarchy; (2) these angels not mere companions of God but His intermediaries, established (often) over special domains; (3) in the philosophical religion, a corresponding doctrine of hypostases; (4) as a result, a remoter conception of God; (5) a developed demonology; (6) the conception of a supreme head (Satan) over the powers of evil; (7) the doctrine of immortality; (8) rewards or punishments for the soul immediately after death; (9) a schematic eschatology especially as regards chronological systems; (10) a superhuman Messiah; (11) bodily resurrection; (12) a rationalized, legalistic conception of God's moral demands.

Nothing wrong or unusual about that--unless you become defensive about your religion and try to put up firewalls intended to keep you hermetically isolated from other cultural and spiritual influences. That kind of deliberate isolation not only never works, but it always has a negative effect on cultural and spiritual and even technological developments. Remember that the words sin and zonde are derived from the same root as asunder and afzondering: think also of  words like apartheid, segregation, and so on--the negative connotations abound, for separation stops the flow of the life giving spirit-energy and the Holy Spirit in particular could get mightily offended by it. So let's get together and not isolate each other because of conceptual or doctrinal differences. All religions need to recognize their shared spiritual basis in what is self evident and begin to come to grips with the fact that doctrinal categories need not become dogmatic straight jackets, but are supposed to help rather than hinder people in their spiritual growth. Instead of a straight jacket, religion should be more like a crutch helpful to those who still need dogmatic structures--as Jesus himself said: he had come to fulfill the law, and those who follow his example need no longer be concerned with the niceties of the law--or of doctrine, but simply live from the heart, motivated directly by love.

If Adam may be seen as the prototype human being, the first one to become egoically self aware (after  ingesting some forbidden substance) by discovering his separate being and awareness from the rest of divine reality--and also began to conceptualize the myriad of other 'seperate things' in material reality to which he related by  giving them names, as the Old Testament says--then surely a mature Christian view of Jesus would see him as the prototype human being who was no longer separate and apart, but integral and whole--who had finally transcended conceptual categories, including that of the egoic self--because he was both religious and  spiritual--both the Word and the Way--both the Logos and the Tao.

I am not presenting this as the truth, but as a contemporary way of looking at the truth through words.

Christianity is not a single religion with a single set of doctrines, it is one of many broad rivers that flow into the ocean, a river with many sources and many branches. But the water that fills the river, its tributaries and its branches as well as all other rivers and even the ocean itself is all one flowing, spiritual subsance--and we are all made of that.

In the Indian tradition that divine reality we are an integral part of is often referred to as Sat-Chit-Ananda: meaning Being-Awarenes-Bliss, and Bliss is what Love turns into when we have transcended all separation--and with it even all relationship--when relationship has become so close and intimate that it has turned into identity.

The highest form of relationship (or soul) is the love of being aware, but the highest identity is the bliss of being aware:  Sat-Chit-Ananda.

Again--don't try to categorize, polemicize, differentiate or minimize--that's not what I am writing this for. Take it as you wish--make the most of it, or discard it if you cannot use it--ieder zijn meug--to each his own.

But if you do ponder on these things, the questions of what are the sources of human religion, who  were the first human beings, what motivated people to create religious narratives and what were the sources of the Abrahamic religions may all find sufficient answers in your own narrative, the narrative of your own soul.

Christianity is really a form of Judaeism, since the Christians believe in the Jewish  Messiah. So to answer the specific question as to the origin of Christianity, one would have to point to the origin of Messianic Judeaism itself. 

While the origin of Judaeism may be traced back to Abraham, the origin of Messianic Judaeism may be found in the absorption of messianic beliefs from the Zoroastrian religion--although the Hebrew word meshiach (usually rendered as messiah, meaning annointed, or christos in Greek) is of Egyptian origin: Ancient Traditions of the Messiah.

While Jesus was neither the first, nor the last of the Jews to make a claim to be the promised Messiah, it was from those who accepted him as such that Christianity eventually arose in its multiplicity of forms. However, as it says in the New Testament itself: In my Father's house there are many mansions--meaning structures, not material structures, obviously, but many conceptual, or religious structures.

Diversity is the norm even in Heaven--it stands to reason, for even heaven, or heavens, are within the realm of manifestation, after all. In spite of all this internal diversity, on earth or in heaven, however, Judaeo-Christianity, Christian Judaeism or Messianic Judeaism could of course be  seen as a single spiritual movement, with many separate doctrinaire systems that not always agree, often clash, but ought to get over their differences--as they ought to get over broader differences with non Christian Judaeisms, specifically Rabbinical Judaeism which developed after the destruction of the Jewish temple in 130 CE (See: Wars between the Jews and Romans) or that third important form of the Abrahamic religions, Islam, with its many branches and variant sets of dogma--and even all other teachings of a religous nature, other religious mansions, built on a spiritual understanding of the whole flow of universal energy, rather than on a materialistic, atomistic understanding.

What we all need to guard against is religious materialism for that is one of the greatest dangers of our time: since it sets one religon against another, as we have seen too often.