The 77 generations

The genealogical truth was, of course, not Luke's real aim. He wanted to show that Jesus was of Davidic descent and could therefore be the Messiah. Luke plays an interesting game in this genealogy, which we can appreciate by comparing his text with its sources.

• Luke started by combining existing genealogies. 
• Genesis 5.3-32 (from Adam to Shem)
• Genesis 11.10-26 (from Shem to Abraham)
• Genesis 25.19-26, 35.23, 46.12 (from Abraham to Hezron)
• Ruth 4.18-22 (from Hezron to David)
• 2 Samuel 5.14, Kings 1 and 2, Ezra 5.2 (from Nathan to Zerubbabel)
• Having combined these family trees, Luke inserted two names. In Genesis 11.12-13 Shelah is the son of Arphaxad; but Luke makes Shelah the grandson of Arphaxad by inserting Kainan. The other addition is Admin. In doing so, Abraham, who had belonged to the twentieth generation, moved to the twenty-first generation, and David moved from generation #33 to generation #35. In other words, Luke introduced a system in which every seventh generation, a special man arose: e.g., Enoch (7), Abraham (21), David (35).
• Finally, he added new names to bridge the gap between David and Jesus' father Joseph. Luke was more or less obliged to mention Zerubbabel, the son of Shealtiel, a descendant of David who played an important role in the development of messianology (more). Shealtiel was probably the son of one of the last kings of independent Judah and therefore a descendant of king Solomon (cf. Matthew 1.6), but Luke makes him a descendant of another son of David, the prophet Nathan.
• The names added by Luke are again highly significant: in the forty-second and the seventieth generation we find a Joseph, in the forty-ninth (7x7) a Jesus. Again, Luke plays with the number seven. Other interesting names are the four patriarchs in generation 42-45. 

One question is: why seventy-seven generations? The answer lies in the First book of Enoch, a collection of texts that share an interest in the patriarch Enoch, about whom it is written that 'he was taken away' instead of 'he died' (Genesis 5.24). This line caused many to think that Enoch had ascended to heaven and had written reports about it.

One of the five parts of 1 Enoch is the 'Book of the Watchers', which was written in the third century BCE. It describes the fall of the angels and their punishment:

And the Lord said to [the arch-angel] Raphael: 'Bind [the rebel] Azazel hand and foot and throw him into the darkness!'
   And Raphael made a hole in the desert, which was in Dudael, and cast him there. On top of him, he threw rugged and sharp rocks. And he covered Azazel's face in order that he may not see light and [...] may be sent into the fire on the great day of judgment. [...]
   And to Michael the Lord said: '[...] Bind them for seventy generations underneath the rocks of the ground until the day of their judgment is concluded.'

[1 Enoch 10.4-6, 11-12;
tr. E. Isaac]

In another part of the First book of Enoch, the 'Book of Similitudes' (first half first century BCE), we learn more about the last judgment. We read how the Messiah, who is said to be created before the universe and is called the 'son of man', will judge mankind, which has risen from the death.

Back to Luke. By making Jesus of Nazareth the seventy-seventh of the list, he is obviously playing with these thoughts. What he is in fact saying is that Jesus was the Messiah and that the last judgment is very, very near. After all, when Luke composed his gospel during the persecution by the emperor Domitian, there were only a few survivors of the generation of Jesus.