Great... Thanks Dunstan, I actually learned something today... Going with this let me ask you:
If a Jew came to believe that Jesus Christ was/is the promised Messiah and came to faith in Him... would he then stop being Jewish and is now a Christian? or is there no hope anymore and we should stop witnessing to them...?
Thanks!
Lorry
In order to properly understand this issue you have to understand first that in the ancient world the concept of ethnicity and race did not exist as it does today.
Today we define people groups by concepts of race and ethnicity, but those really had no meaning in the ancient world. What mattered to the ancient was nationality and family. Thus a person was Greek, or Roman, or Jewish, not because of their actual genetic ethnicity or race, but because of their membership in either that nation/city.
Jewishness was primarily defined in two ways, one was familial relationship and the other was religion. Israelites, or Hebrews, were people descended from Abraham and his sons. Jews were specicially those descended from the tribes that made up the nation of Judah.
But religion for the Jews/Israelites was also a family matter because their religion was covenant based and covenant is a binding oath that forms a family bond. So, in order to truly be an Israelite and/or a Jew one had to be both of the family and the faith.
Of the two, the primary and most important was the faith. It was possible for those who were not physical descendants of Abraham to join the Jewish faith, and as a result they were considered to be Jews.
Thus for Jewishness, the most important thing is membership in the covenant.
Paul taught that membership in Abraham's covenant (and thus Abraham's family) was defined by faith in God, not by genetic descent. This idea is actually not knew to Judaism it is pretty much what Judaism taught all along. Though not as prominantly or perhaps as explicitly.
The real revolution was the belief that Jesus Christ was God, thus faith in Jesus Christ became the defining point of being a member of Abraham's covenant family.
So, according to Christian doctrine, all Christians are Jews because we are members of Abraham's covenant family by faith in Jesus Christ. So from the Christian point of view, when a Jew becomes a Christian, they are simply coming home.
Now, many Christians, especially historically, have used this to teach that the Christian Church replaced Israel (meaning 'natural' physical Israel). The bible doesn't really teach this when considered as a whole.
The more accurate view, (IMO of course) is that the Christian Church is a continuation of Israel. We are joined into them and we continue what they began.
Thus Israel in the natural sense are still chosen of God, but they are in rebellion at the moment and eventually they will come back home to the Church which is the continuation of the Congregation of Israel.