|A visual of the artistic form change of "Set", the Egyptian god of evil (1700BC), a red-skin colored fallen god, who does battle each night with the sun god Ra, in the form of a serpent, to the "Devil", the Christian angel of evil, a red-skin colored fallen angel, who also appears in the form of a serpent, who does battle with the forces of good, in modern terms.|
Set | Fallen angel
The modern concept of the Devil, in the Abrahamic religions, is derived from the Egyptian god Set, a god typically described as "horned", with “red or reddish-brown hair or skin”, who is a fallen god. 
In 1879, Peter Renouf, in his Origin and Growth of Religion: as Illustrated by the Ancient Religion of Ancient Egypt, summarized Set’s fall from grace, as a leading god, as follows: 
“Set, though the antagonist of light in the myths of Ra, Osiris and Horus, is not a god of evil. He represents a physical reality, a constant and everlasting law of nature, and is as true a god as his opponents. His worship is as ancient as any. The kings of Egypt were as devoted to Set as to Horus, and derived from them the sovereignty over north and south. On some monuments one god is represented with two heads, one being that of Horus, the other that of Set.”This two-head depiction (with description) is as follows: 
“The name of the great conqueror, 'Seti' [1290BC] signifies 'he that is devoted to Set.' It was not till the decline of the Empire that this deity came to be regarded as an evil demon, that his name was effaced from monuments, and other names substituted for his in the ritual.”
In 1883, Frederic Hall, in his The Pedigree of the Devil, citing Renouf, summarized the Set as fallen god turned “devil” or demon figure as follows: 
“Set was the devil of the later Egyptian mythology.”
Christianity also over-typically describes the Devil as a "fallen angel" who terrorizes the world through evil.  This refers to the fall of the god Set from good god to bad god after 18th dynasty Egypt; Wallis Budge (1904) summarizes as follows: 
“In the early dynastic times, it is tolerably certain that the worship of Set was widespread, and his cult seems to have flourished until the period which lies between the XII and the XVIIIth Dynasties; but about BC 1700 a change came over his fortunes, and the Egyptians began to show the greatest detestation for him. He had, of course, always been connected with evil, but it appears that the popularity of his cult suffered greatly at this period because he was associated with the occupation of Northern Egypt by the Hyksos, who identified him with certain Semitic, Syrian gods.”
Set, in other words, originally, in 1st dynasty Egypt (3,100BC), was the great god of Southern Egypt who battled Horus, the great god of Northern Egypt, for rule of the Empire. Horus, according to the famous "Passion of Osiris" one in the end and therein proclaimed the right to rule Egypt, which is why most of the early dynasty pharaohs had Hor (or Horus) as part of their name. Set, after the fall of Hyksos dynasty, which was in power in Egypt from 1650 to 1550BC (see: supreme god timeline), went from being a "chief god" to a fallen god. Then, in the course of the Hebrew recension (see: recension theory), a polytheism to monotheism religious reformation, wherein lesser gods were reshaped into the guise of either angels, demons, of fictional humans, Set went from being a "fallen god" to a "fallen angel".
Set | Red color
In 1970, Jeffery Russell, in his The Devil: Perceptions of Evil Antiquity to Primitive Christianity, stitched together connections between Set and the Devil; in particular, Russell notes that the "red color", contrary to the modern view that the red of the devil has to do with the red color of the flames of hell, originated from the death-bring "red" color of the hot dessert sand, surrounding the fertile part of Nile region, as opposed to the life-giving (crop-growing) "black" soil, called keme, brought down from the Ethiopian Mountains, each Nile flood season: 
“No deity ever becomes the principle of evil, but in one god, Seth [Set], the destructive and unharmonious element is more evident than in others. The myth of Seth as the antagonist of the sky god Hor or Horus (hor = ‘face’ or ‘sky’) is as ancient as the Pyramid Texts; the hostility between the two grows in time, and finally in the Hellenistic period [323BC-30BC], Seth has become almost entirely evil. Some scholars interpret the origin of the myth as political: Horus is a god of lower Egypt, the north, and Seth is a god of upper Egypt, the south. Others insist that Seth and Horus (or Osiris in the myths) are deities of opposite ecologies, Seth representing the dry desert and Horus or Osiris the black earth [keme] or the fertilizing Nile. Egypt is one of the few cultures in which black is not the color of evil, but the color of the fertile, life-giving alluvial plains of the delta. Red was the evil color, the hostile hue of the scorching sands. Because of Seth's association with the desert, his color most commonly is red, and red-haired or ruddy people were considered in some special way his own.”
Set | Horns
In 1978, Anthony Mercante, in his Who’s Who: in Egyptian Mythology, elaborated on Set as follows: 
“Set is sometimes portrayed with horns, which made him the ideal image for the devil in Egyptian Christianity.”
Set | Snake & Tree
In modern terms, Christianity identifies the Devil ("Satan") with the Serpent who tempted Adam and Eve to eat the forbidden fruit.  This refers to the characteristic of Set in the form of Apep the snake that does battle with Ra the sun god, in and around the Persia Tree [see: Christmas tree], each night. 
Set | Namesakes
Set assumed many names, one of the first of which was Baal; Wallis Budge (1904) summarizes this as follows: 
“In the North and South of Egypt, Set was called both Nubti and Sutekh, , and there is no doubt whatsoever that he was endowed by the peoples in the Delta with all the attributes of the Semitic god Baal, בעל, whose name appears in Egyptian under the form Bar, or Balu .”
The history of how Set subsumed Baal in namesake became the modern day namesake "devil" (or Satan) is involved; Matthew Chris, in his Modern Satanism (2009) gives a fairly cogent synopsis of this overall recension as follows: 
“Satan's ancestry is the result of an elaborate cross-breeding of traditions that has spanned millennia. Numerous faiths and folklores have contributed to his bloodline as it has passed through history, creating a figure rich in resonance and lore. Though widely regarded in the present day as a single supernatural entity, the preeminent embodiment of evil, Satan is actually a reduction or hybridization of a number of individual demons and mythical beings. The list of his progenitors, kinsmen and co-conspirators includes Lucifer, Mephistopheles, Beelzebub, Belial, Azazel, the Devil, various lesser devils, Ahriman, and even the Egyptian deity Set (Seth). This impressive gallery of seducers, liars, and destroyers gradually coalesced into the grand figure of the archfiend as he is now known, the great adversity of god and humanity.”
Set, as the antithesis of light, over the course of the last 5,000-plus years, in short, via religious recension, redaction, and synretism, became the modern religious mythical figure of the "devil", the embodiment of evil.
In 2011, in the supernatural horror-thriller The Rite, staring Anthony Hopkins, the agnostic-skeptic American priest in training Michael Kovak (Colin O'Donoghue) is only able to “exorcise” the demon, using the “knowing the name” technique of the Egyptian human model, by speaking the secret name of the demon, at the end of the movie, which is Baal. (Ѻ)
The following are related quotes:
“I do not intend to do here what other scholars already have done well. Jeffrey Russell  and others, e.g., have attempted to investigate cross-cultural parallels between the figure of Satan [Devil] and such figures as the Egyptian god Set or the Zoroastrian evil power Ahriman. What interest me are the specific social implications of the figure of Satan.”— Elaine Pagels (1995), The Origin of Satin 
1. Budge, Wallis. (1904). The Gods of the Egyptians, Volume Two (§:Set, pgs. 241-60; Horus-Set double head image, pg. 242-243; Apep, pg. 245; fallen angel, pg. 250; Baal, pg. 250). Dover, 1969.
2. Russell, Jeffrey B. (1970). The Devil: Perceptions of Evil Antiquity to Primitive Christianity (Seth, 13+ pgs; quote, pg. 78). Cornell University Press, 1987.
3. Pagels, Elaine. (1995). The Origin of Satan (pg. xviii). Vintage Books.
4. Leeming, David. (2005). Oxford Companion to World Mythology (Devil, 22+ pgs). Oxford University Press.
5. Mercante, Anthony S. (1978). Who’s Who in Egyptian Mythology (editor and reviser: Robert Bianchi) (pg. 144). Metro Books, 1995.
6. Renouf, Peter Le Page. (1879). Lectures on the Origin and Growth of Religion: as Illustrated by the Ancient Religion of Ancient Egypt, Hibbert Lectures (pgs. 117). Publisher.
7. Hall, Frederick T. (1883). The Pedigree of the Devil (pg. 130). Publisher.
8. Mathews, Chris. (2009). Modern Satanism: Anatomy of a Radical Subculture (Earliest Origins, pg. 2). Greenwood Publishing Group.
● Devil – Wikipedia.
● Beelzebub – Wikipedia.
● Baal – Wikipedia.