Radak (Rabbi David Kimchi) explains Isaiah 53 except for the final two verses, as the “Words of the Other Nations”. These words are not Isaiah’s words. Evidently, this is recorded to understand the view of the Gentile Nations at that time. What is the Christian response?
It should not surprise anyone that a Jewish teacher would try to suppress the obvious–that Isaiah 53 is a prophecy about Jesus of Nazareth. To accept the obvious implication that the writer of Isaiah prophesied the means, purpose and result of the death of Jesus, the Messiah is to accept that one must leave Judaism and become a Christian. Anyone who does not do this must come up with some reason to reject the obvious interpretation. So, I do not mind reading what Jews have to say about Isaiah 53. It can actually be helpful, but I understand that whatever they say, it is coming from a presupposition in opposition to the actual meaning.
In any case, whether the historical person Isaiah actually wrote these verses, or some other person/group, as even some Christians have proposed, this does virtually nothing to change the fact that Isaiah 53 is a prophecy about the Messiah. Arguments about who wrote this passage do not seem to affect the interpretation significantly. Jesus is the one who was pierced. Jesus is the one who was despised and rejected. Jesus is the one who was silent before his accusers. Jesus is the one who was assigned a grave with the rich (Joseph of Arimathea), Jesus is the one who was resurrected and who “will see his offspring and prolong his days.” This is a prophecy about Jesus of Nazareth–the Messiah–and any attempt by Rabbi Kimchi to shift the argument to the identity of the author does not change this conclusion. Who wrote this messianic prophecy seems to not matter very much.
Besides, where is the marker in this passage that shows that this is the view of the Gentile nations? Where is the style break to note this? What verse begins this Gentile-inspired section? Why does Kimchi switch back to it not being the “view of the Gentile nations” after Is 53:10? It seems to me that this is reading a presupposition into the text, rather than finding something from the text. It seems arbitrary to me and to have been done in order to support a theory. It seems ad hoc to me, and not supported by the text itself. But, like I already said, even of Kimchi were correct, this does not change the nature of the extremely obvious prophecy about the person Jesus of Nazareth.