How’s it going?
Today, I am writing to you to give you some information about ‘the servant of the Lord (or Yhwh)’ mentioned repeatedly in Isaiah 40-55 that you asked me the other day who it is. I read and listened to some resources of “the servant” in Isaiah 40-55, which is called ‘Second Isaiah,’ to find an answer to your question. As a result, I found some information about Second Isaiah in general as well as about “the servant” in it.
First of all, I found that the author of these chapters of Isaiah who lived in Babylonian exile in the mid-500s BCE is not the same prophet of Isaiah 1-39, who lived in the 700s BCE in Jerusalem, from what I read in Bandstra. In fact, I didn’t know it before I read it. You can see some reasons to support this when you read 40:1-2 in its reference to the destruction of Jerusalem as a past event, in 43:14, 48:20, Babylonia is described as its present setting, and in 44:28, 45:1-4, Cyrus the Persian is mentioned as their coming deliverer. Bandstra also asserts that this prophet is one of the most inspiring of the Hebrew Bible in his synthesis of traditions and his original and brilliant poetry to draw from Israel’s historic faith, reapply it to the new setting of exile, and give the refugee people of Yhwh reason for hope.
In addition, Bandstra mentions that the prophetic anthology of Second Isaiah is called “the book of Comfort” based on passages like what you read in 40:1-2, 6, 8, which starts with the phrase “Comfort, comfort my people!” and which is expressed in some of the most beautiful and fascinating poetry in the Hebrew Bible. In another resource of reading, I found that Second Isaiah prophesied at the time of hope in the history of Israel and Judah living in Babylonian exile toward the end of the exilic period, which might be related with the fact that the main theme of Second Isaiah is consolation. 
As for “the servant of Yhwh” in Second Isaiah, I discovered a prevalent interpretation about it in the materials that I read and listen to. Among them, Dr. Lester’s lecture of “Response to Exile B,” which I have been listening to for the online course of “The Introduction to the Hebrew Bible,” provides an interpretation of “the servant” as the most famous figure of Second Isaiah, repeatedly mentioned as “my servant”, referring to “Israel,” sometimes called “Jacob” (41:8-9; 42:1-4, 19; 44:1-2, 21; 45:4; 48:20; 49:1-6; 50:4-9; 52:13-52:12). According to the lecture, in these verses of the given chapters, “the servant of the Lord” is interpreted as “people of Israel,” which is clearly mentioned in 41:8; 44:1-2; 44:21; 45:4.
However, as you can guess, there is a resistant opinion against this interpretation of “the servant” as “Israel”. It is the Christian reading tradition that considers the exilic Israel as a sinner that needs judgment. Dr. Lester introduces a theory of Bernard Duhm in 19th CE as one of its leading scholars that the part of “the servant” called explicitly “Israel” which describes “the servant” as suffering in the servant’s innocence must not be the original part of Second Isaiah, but a later addition to it. Duhm suggests the verses of the so-called servant songs, Isaiah 42:1-4; 49:1-6; 50:4-9; 52:13-53:2, imply some other figure, not Israel. However, Dr. Lester asserts that there is no manuscript evidence that verifies such a decision that these were not the original verses of Second Isaiah and that these songs have very coherent and naturally organic place in the surrounding texts.
I found also this interpretation of “the servant” as “Israel” in the Harper Collins Study Bible that I consult for understanding the verses from the Bible; among the Servant Songs in 52:13-53:12, as the last and most striking of the so-called servant songs, it says that the servant appears to be have been exiled Israel in the original historical context. However, the Harper Collins Study Bible also presents the early church’s interpretation of “the servant” in this passage as Jesus Christ as used in Acts 8:32-35, and suggests that Jesus’ own sense of identity and mission may have been shaped by this figure as you can find in Mark 8:31; 9:30-32; 10:33-34.
Among the resources that I read, Bandstra suggests various possible interpretations of “the servant of Yhwh”; the servant of Yhwh can be a metaphor for Judah suffering in Babylonian exile in that Judah conveyed healing to other nations by witnessing the saving power of Yhwh; another possibility of the servant is an actual individual, that is, a real prophetic figure, such as Jeremiah or Second Isaiah himself; the Christian interpretation is Jesus of Nazareth, which can be noticed in the use of Second Isaiah in Handel’s The Messiah (p351).
Stanley also presents the debates about the identity of “the servant of Yhwh”; Christians’ claim of its pointing to the coming of Jesus in Isaiah 53; scholars’ division over whether the term refers to an individual, as Bandstra mentions, most likely the prophet, or to Israel in figurative terms as a person (p461). Stanley provides the verses to support each position of the scholars, which is compatible with that of Bandstra, as you can guess.
Finally, there is one more resource of reading that strongly claims “the servant” in Isaiah 53 to be “the nation of Israel “who silently endured unimaginable suffering at the hands of tis gentile oppressors. It is “the rabbinic interpretation of Isaiah 53” by Tovia Singer, who insists that the reference of “the servant” in Isaiah 52-53 as “the nation of Israel” is understandable in its connection to the preceding chapters of the three Servant songs in addition to the verses including explicit calling as “Israel” or “Jacob”, as mentioned above.
All these resources that I found about the interpretation of “the servant of the Lord” in Second Isaiah show that the understandable interpretation of “the servant of the Lord” in the original historical context appears to be ‘exiled Israel’ as mentioned in the Harper Collins Study Bible and the other resources and that there are more possible interpretations regarding the context of the verses that the term is used, such as the Christian interpretation of the term as “Jesus of Nazareth” based on the citation or application of the content of Isaiah 53 in the New Testament.
I hope this information will be help for your understanding of “the servant of the Lord” in Second Isaiah as it is great help for mine.
Young Sun Lee
 Christopher D. Stanley, The Hebrew Bible : A Comparative Approach. (Minneapolis: Fortress Press, 2009), 461.