Here's a thought-provoking piece from the National Review where author-journalist David Klinghoffer argues that the Jews rejecting Christ was the turning point in Western history:
Because the earliest Christian church was initially hobbled by insisting that new converts adhere to Jewish law — keep kosher, be circumcised, etc...The decision was made, however — at a church council in Jerusalem in 49 — to jettison Jewish law as a requirement for new Christians. This was done at the apostle Paul’s insistence, and he explains in Acts that since the Jews were rejecting his presentation of Jesus as savior and messiah, the Christian message would now be taken to the gentiles. Dispensing with Jewish practices like circumcision made this possible. Had the Jews not rejected Paul’s preaching about Jesus, the church likely would have held on to those laws. Had it done so, the church would have remained hobbled, and could hardly have become the world-bestriding institution it is today. Jewish Christianity would have remained a sect in Judaism, and probably would have died out along with other such sects in 70 when the Temple was destroyed by Rome and the Jews scattered. In that case, there would be no Christian civilization, and, among other things, no America as we know it — a country whose founding was deeply influenced by Christian faith.
This is not meant at all to kindle a debate on Judaism and Christianity on which I am certainly no authority. But the concept of 'turning point in history' has always held a special fascination.