Unless you can understand that it Fundamentally doesn't matter that Jesus was a Jew, you haven't Really grasped Christianity

This, for reasons I explain here. 

Furthermore; I also indicate why the Old Testament is also inessential to what Jesus did, and being a Christian. 

Of course, as individuals, Jesus being a Jew and the historical link with the ancient Hebrews and their Law is interesting, influential, and may have personal validity and helpfulness on an individual basis. As may many other contingent and inessential matters such as one's own race and nationality.

(For instance: Englishness and England are, in this contingent way, both very important to me personally.)  

I think this clarity about ultimate and fundamental things has become ever-more essential, especially in recent years.