The mere mention of Lucifer often strikes dread in the hearts of believers while arousing the scent of searing sulfur and eternal punishment. “He” is seemingly forever synonymous with Satan; although the two terms are not entirely equivalent to each other. Etymology is necessary to unravel the historicity of how the word “Lucifer” became adopted by early Christians.
Lucifer is derived from the Latin phrase “lucem ferre,” which means “bearer of light.” The 4th century Vulgate is a Latin translation of the Hebrew bible (its authorizer was Pope Damasus I) and there you will find that “Lucifer” translates literally to “son of the morning,” or “the planet Venus.”  The Hebrew word hêlêl—that the Vulgate deems as “Lucifer” in Isaiah 14:12—does not represent an all-pervading corporeal creature with cruel powers to possess and seduce souls. The Septuagint, a 2nd century BCE Greek translation of the Hebrew Bible, also represents hêlêl as meaning “Day Star,” which is another fancy term for Venus. 
Ironically, modern versions of the Bible refer to Jesus with the infamous “morning star” title (New Living Translation, King James Bible, Jubilee Bible 2000, English Revised Version, etc.):
Revelation 22:16 – “I, Jesus, have sent My angel to testify to you these things for the churches. I am the root and the descendant of David, the bright morning star.”
Matthew 2:2 – “Where is the one who has been born king of the Jews? We saw his star when it rose and have come to worship him”
Revelation 2:28 – “I will also give him the morning star.”
This may all seem strange, but just remember that cultures throughout recorded history have always given planets and constellations great roles of grandeur. The visible planets in our solar system were gods to the ancient Romans, to whom they prayed and offered propitiations to with reverence. Various strains of cults that worshiped the sun can be found on nearly every continent. It’s evident that personification is the oldest trick in the book for humans to familiarize the internal perception to the external world.
Since Lucifer is at least a bit more understood, let’s scrutinize “Satan.” Long ago an early Christian scholar and theologian, Origen (185 – 254 ACE), was convinced that Azazel in Leviticus 16:8 was the Christian Satan (Contra Celsus, vi, xliii). Some contemporary scholars not only agree with Origen’s assertion, they have also applied an intricate historical correlation: Azazel was probably influenced by the pre-existing Canaanite gods known as Attar and Mot. 
The Ba’al poem depicts Attar descending from the throne of heaven by his own shame and unfit prestige (while the Christian counterpart descends from heaven due to a revolt). According to Peter C. Craigie, who translated Ugaritic texts during his research, the god Attar could’ve possibly represented Venus to the Canaanites.  And coincidently, the Isaiah 14:12 passage of “morning star” was probably a Babylonian King—and Attar was also, as the legend goes, a Babylonian King.
Daniel Wallace once wrote an article for Bible.org that included the following:
“The reality is that in Isa 14:12 the primary or initial reference of ‘morning star’ is not to the devil but to the Babylonian king. The footnote in the NET Bible here says, “What is the background for the imagery in vv. 12–15? This whole section (vv. 4b–21) is directed to the king of Babylon, who is clearly depicted as a human ruler. Other kings of the earth address him in vv. 9ff., he is called ‘the man’ in v. 16, and, according to vv. 19–20, he possesses a physical body.”
“The morning star literally referred to Venus, but in ancient times it was used metaphorically of earthly kings. The note in the NET Bible at 2 Peter 1:19 is helpful along these lines: ‘The reference to the morning star constitutes a double entendre. First, the term was normally used to refer to Venus. But the author of course has a metaphorical meaning in mind, as is obvious from the place where the morning star is to rise— “in your hearts.” Most commentators see an allusion to Num 24:17 (“a star shall rise out of Jacob”) in Peter’s words. Early Christian exegesis saw in that passage a prophecy about Christ’s coming. Hence, in this verse Peter tells his audience to heed the OT scriptures which predict the return of Christ, then alludes to one of the passages that does this very thing, all the while running the theme of light on a parallel track. In addition, it may be significant that Peter’s choice of terms here is not the same as is found in the LXX. He has used a Hellenistic word that was sometimes used of emperors and deities, perhaps as a further polemic against the paganism of his day.’” 
Judit M. Blair’s 2008 thesis on Old Testament demonology offers, on page 17, an interesting dissection:
“For example, he concludes that the se‘irim in Lev 17:7, 2 Kings 23:8, and 2 Chron 11:15, are creatures of ‘demonic’ character since the Arabs, Babylonians and Assyrians ‘frequently conceived of demons as assuming the form of animals which haunted ruins and desolate places’ and these were ‘portrayed as hairy beings’. The se‘irim in Isa 13:21 and 34:14 must be referring to more than ‘mere natural animals’ since they are mentioned along with Lilith, and ‘we have seen that Lilith appears as a notable demon in Babylonian Demonology’ (pp. 39-40)…Azazel is treated similarly…So in view of Arab and Babylonian beliefs it is natural to conclude that the passage contains an ancient Semitic belief in desert demons, and Azazel can be explained as ‘a Semitic god of the flocks who was later degraded to the level of a demon under the influence of Yahwism’ (pp.43-56).” 
The founders of the monotheistic mythologies, however primitive they may have been, were men who tried their best to explain the world around them. They looked to the heavens in awe of the Universe’s majesty, giving allegorical stories to the celestial bodies and adapted older fables from generations past to suit their needs. Should we blame them for their ignorance, for their lack of knowledge? Should we freely mock their fantastic myths of supernatural beings? Maybe, but perhaps, in that feeble-minded realm of simplicity, you and I too would have resorted to similar personification without our current wealth of science and understanding. Would we, molded by tradition and culture, have been all too accepting to such fantastic claims? Indeed, that odious possibility might hold merit.
 Peter C. Craigie, “Helel, Athtar, and Phaethon,” p. 223.