Obviously, the New Testament per se is not required -- Jews today don't go around engaging in massacres of the sort described in the Biblical account of the original conquest of Caanan.
Realistically, what civilizes a religion (or any other major institution) is some counterveiling force that prevents it from wreaking evil, or at least penalizes it significantly for doing so. In the case of Christianity, the civilizing process was a fallout of struggles between Church and State and (particularly after that German monk tacked his notions up on a church door) between church and church.
True enough, but ask yourself if the future of the Jew would have unfolded differently has they moderated their religion as did Christianity at about the same time frame.
Would not the Holocaust be missing from the historical record? Would not the exodus (small "e")of Jews from the all of the Arab and Muslim territories not have occurred if Islam had done likewise? Would not the present have no need for the Jewish State of Israel.
This is all just speculation of course, but had these other two major religions done the same thing that Christianity did and modified their founding dogma with the story of Jesus which all three religions currently recognize, the world would be a totally different place today. And this cannot be denied.
Woulda, coulda, shoulda.............
But the idea of it emphasizes that what we are experiencing today is a continuation of a religious war started some 1200 years past, and only one of the three religions involved has truly evolved to prevent this sort of thing. This does not mean that the other two have done nothing or made no attempts to do so, but they have generally failed because for them the war never stopped. It has been perpetual.
This brings the question:
Can they ever stop?
I think they can, but it seems to me that many feel otherwise. I think the right thing to do is to try harder and realize that this will take many more generations of failures and successes to stop this ball from rolling. Unfortunately, even talking about this has been like farting in the wind. You get attacked by all three sides and the war continues....