Genesis 14 has a remarkably different theme and perspective on Abraham's life that is shown in other chapters. Here, Abraham seems less like a peaceful patriarch, and more like an important tribal warlord. The text also contains the primary reference to the figure of Melchizedek, who would become a favorite figure for the wildest of speculations from later religious leaders and authors.
The text shows no evidence of having been written by any of the more familiar Biblical sources, J, E, or P. Textually, it is filled with unique vocabulary and grammatical structures. Grammatically, the text itself hints at having been translated from an older Akkadian source, especially in verses 1, 7, 14, and 23. And there are other reasons to suppose that the text is the work of a non-Israelite outsider, (just as one example among many, Abraham is referred to as "Abram the Hebrew", a term most often applied to the family by outsiders).
The text also seems to hint of an authentic historical setting. For example, the cities mentioned all are authentic names from the correct time period and setting, not the sort of names that later authors would have realistically been able to invent.
None of this evidence by itself is terribly convincing, however, when taken as a whole, the evidence points to some startling implications for the historicity of Abraham himself. What we may have before us in Genesis 14, could be the next best thing to finding an independent external and contemporary Akkadian reference to the person of Abraham in the writings of Israel's neighbors!
Perhaps ironically enough, a historically contextual view of Genesis 14 also clearly demonstrate the fallibility of the later Biblical authors, who badly misinterpret this passage, especially as it relates to Melchizedek.
Melchizedek is presented in the text as an important Canaanite king/priest, the ruler of the Salem city state, presumably Jeru-salem (literally, the city of Salem) before the Israelite conquest. In that context, it would make sense for Abraham, as a tribal war lord, waging a military campaign in Melchizedek's general territory, to assure Melchizedek that Abraham was not setting himself up as a military rival. To that end, Abraham appears to have shared a covenant meal with Melchizedek, and paid homage to Melchizedek as his political superior, giving him a tenth of the spoils of the conflict waged in Melchizedek's territory. As we would expect from a Canaanite city state king, Melchizedek invokes an authentic Canaanite deity in this exchange (El Elyon) that is well attested in both Ugaritic and Phoenician sources.
Later Biblical authors falsely assume that Abraham would not pay "tithes" to a pagan, and they therefore assume that El Elyon must be another name for Jehovah (this despite the obvious impossibility of turning the king of a Canaanite city state into a worshiper of Jehovah). This same argument is used by the late author of the New Testament book of Hebrews, who argues that Abraham would not be paying tithes to Melchizedek, unless Melchizedek held a priesthood that was both higher, and more ancient than the one that Abraham's descendant Aaron held. This is the foundation of the Book of Hebrew's argument for the existence of a non-Aaronic priesthood that Christ held, that allowed him to function as a "better High Priest" despite his not being a descendant of Aaron. Instead, Christ was thought of as a priest "after the order of Melchizedek." This "better" High priest was able to perform the functions of the Day of Atonement in a better (heavenly) temple, and thereby cleans the world of sin permanently, instead of having to repeat the ritual annually as the High Priests of Aaron had to. Unfortunately for the author of Hebrews, (and for those who cling to Biblical inerrancy) the entire argument is based upon a rather serious and fundamental misunderstanding of the text of Genesis 14!
This sort of misinterpretation of Genesis 14 is not just found in the Biblical authors. It is present in the writings of later religious figures as well. As just one example, the Mormon prophet Joseph Smith Jr. includes a lengthy discourse on Melchizedek in his Book of Mormon (see Alma 13) that is based upon the same central misunderstanding of the nature of the meeting between Melchizedek and Abraham. That mistake is also found in the Joseph Smith's Translation of Genesis 14, and in Joseph's revelation on the priesthood which states that one order of the priesthood was called the Melchizedek priesthood "because Melchizedek was such a great high priest. Before his day it was called the Holy Priesthood, after the Order of the Son of God. But out of respect or reverence to the name of the Supreme Being, to avoid the too frequent repetition of his name, they, the church, in ancient days, called that priesthood after Melchizedek, or the Melchizedek Priesthood" (D&C 107:2-4). This view does not make sense, once one realizes that Melchizedek was a Canaanite king/priest, and not a worshiper of the Israelite god Jehovah at all.
E. A. Speiser, "Genesis: Introduction, Translation, and Notes (The Anchor Bible, Vol. 1)"
YouTube lecture on this subject given at the UU Church of Los Alamos, January 20, 2019