Joseph and Aseneth is essentially a romance novel with the issue of conversion to worshiping the God of Israel as a central concern. It was likely written in Greek in the Jewish diaspora sometime between 100 BC and AD 125. There is an English translation in Charlesworth’s Old Testament Pseudepigrapha, one available online, as well as a recent German translation. The Greek style is strongly reminiscent of the Septuagint (LXX). Before discussing the issue raised in the title, it is worthwhile to give a little further consideration to this work as it stands on its own as it is both a fun story and an interesting work of literary theology in its own right.
Joseph and Aseneth (Jos. Asen.) is extant in a variety of languages, with Armenian having the most extant manuscripts. In Greek there are two distinct versions, called the longer and shorter recension. Recent text-critical scholarship has argued that the longer recension is actually the more basic version, with the shorter one being created by Medieval scribes.
Summary of the Story
Aseneth, the biblical אָסְנַת/Ασεννεθ (Asenath/Osnath in Hebrew; Asenneth in LXX), is the wife that Joseph receives from Pharaoh in Genesis 41.45 and who gives birth to Ephraim and Manasseh. In Jos. Asen., we get a backstory on Aseneth and her marriage to Joseph. She was the daughter of a fantastically wealthy priest and all the sons of all the kings around, including the son of Pharaoh, wanted to marry her because she was so beautiful. After meeting Joseph, seeing how incredible he was, and receiving a blessing from him, she spends eight days in mournful repentance, after which she is visited by an angel who looks just like Joseph, only with a blazingly shiny face. Her prayer of conversion is an inspiring prayer of piety. After her conversion, she marries Joseph, to the great disappointment of the son of Pharaoh. During the famine, Joseph and Aseneth go to meet Jacob at Goshen. The son of Pharaoh concocts a crazy plot to kill his father and abduct Aseneth and force her to marry him. He gets Dan, Gad, Naphtali, and Asher to help him. She is delivered by Benjamin and Leah’s sons. Pharaoh’s son dies from his injuries (he got walloped on the head with a rock thrown by Benjamin), Pharaoh dies of grief, and Joseph gets to be the interim-Pharaoh of Egypt for 48 years.
Joseph vs. Pharaoh’s Son: A Prominent Plot-Arch in Jos. Asen.
One of the literary structuring devices framing this story is the contrast between Joseph and the Son of Pharaoh. Not only is this interesting from the perspective of reading this story on its own, but it also plays very prominently in the question of the usage of πρωτότοκος. We first meet Joseph in 1.1, as he is traveling around Egypt collecting Pharaoh’s grain. He has no interest in women, beautiful Egyptian or of any other sort. We meet the Son of Pharaoh as one of the potential suitors for Aseneth in 1.7, where he is called ὁ υἱὸς Φαραὼ ὁ πρωτότοκος (“the firstborn son of Pharaoh”). He pleads with his father to give her to him as a wife, but, since she is not royal, it is out of the question. Pharaoh’s son drops out of the picture while the focus is on Aseneth meeting Joseph and becoming a worshiper of Israel’s God. In the first twist, Pharaoh gives Aseneth to Joseph as a bride (21.2-8) in a ceremony where he acts suspiciously like Joseph’s father (indeed, Joseph says at some point that Pharaoh is “like a father to me”).
Pharaoh’s son reenters the picture in 23.1, where he is again called ὁ υἱὸς Φαραὼ ὁ πρωτότοκος (maybe this is important, huh?). He sees Aseneth and Joseph from afar and hatches the plot already mentioned to take the throne and Aseneth, but God foils his aspirations. The story ends, as already mentioned, with Joseph sitting on the throne of Egypt (29.9) instead of the “firstborn son of Pharaoh” who ought to have been there.
From a literary perspective, this is a neat case of characters following mirror-image plot-archs, with the underdog coming out on top. Despite its fairly wooden Greek, the story of Jos. Asen. manages to be a well-crafted story, with a center point being the obvious religious concern with conversion from the gods of Egypt to the God of Israel. The plot arch of Joseph frames the story, even though he is not the main character.
Πρωτότοκος in Jos. Asen. and Col 1:15
Finally, we come to the observation of most interest to readers of the New Testament (NT), which is tied up completely with the contrast between Joseph and the Son of Pharaoh. As already noted, the Son of Pharaoh is called multiple times ὁ υἱὸς Φαραὼ ὁ πρωτότοκος. This is obviously because he is the first-born son, the heir to the throne. In a significant passage, Joseph is called ὁ υἱὸς τοῦ θεοῦ ὁ πρωτότοκος “the firstborn son of God” (21.3). Obviously, within this story this is meant as a contrast with ὁ υἱὸς Φαραὼ ὁ πρωτότοκος. Any possible messianic implications from this work are not the concern now. From the perspective of reading the New Testament, the fact that πρωτότοκος is used in two distinct senses in this work—which is from approximately the same time as the NT writings—is significant. In Colossians 1.15 Paul writes of Jesus that he is εἰκὼν τοῦ θεοῦ τοῦ ἀοράτου, πρωτότοκος πάσης κτίσεως (“the image of the invisible God, firstborn of all creation”). One understanding of this text, famously propounded by a certain Arius, is that Jesus was the “firstborn” in the sense of ὁ υἱὸς Φαραὼ ὁ πρωτότοκος, that is, that he was God’s first “offspring” in the creation of all things. This is obviously a possible usage of the word. The traditional Christian understanding, by contrast, is that Jesus is “firstborn” in the sense of Joseph being ὁ υἱὸς τοῦ θεοῦ ὁ πρωτότοκος. That is, he is firstborn not in reference to generation (Joseph is not God’s son in the sense that Pharaoh’s son is the son of Pharaoh), but in reference to his identity: he is the highest, most honorific, etc.
Looking at the usage of this word in Jos. Asen. does not solve the interpretation of this passage (remember, this debate was being carried out by native Greek speakers, who presumably were much more aware of the different usages of this word than we are today). However, it shows a brief glance into the value of reading non-NT texts in order to understand the thought-world in which the NT arose (let alone, to get a better grasp of the language).
 Christoph Burchard, Joseph und Aseneth, Pseudepigrapha Veteris Testamenti Graece 5 (Leiden: Brill, 2003), 39. See also Angela Standhartinger, “Recent Scholarship on Joseph and Aseneth (1988-2013),” Currents in Biblical Research 12, no. 3 (2014): 354 on the language and date of composition; the entire article is a worthwhile read.
 See Burchard, Joseph und Aseneth, 2–8 for a list of the manuscripts.
 The longer is the text of Burchard cited in note 1. The shorter recension is found in Marc Philonenko, Joseph et Aséneth: Introduction, texte critique, traduction et notes, Studia Post-Biblica (Leiden: Brill, 1968).
 See Uta Barbara Fink, “Textkritische Situation,” in Joseph und Aseneth, ed. Eckart Reinmuth, Scripta Antiquitatis Posterioris ad Ethicam REligionemque pertinentia, XV (Tübingen: Mohr Siebeck, 2009), 40.
 All verse numbers are according to Burchard’s text. Unfortunately, the verse numbers often vary drastically between editions, though the chapters are generally the same.