I believe some prophets of God, such as Moses and Elijah, are in heaven, yet they lived and died before Christ came. How is this possible? What does this mean for the other Jewish people?
The basic answer is that there is no difference. Old Testament people, Jew or Gentile, who believed in a coming Messiah were saved. Old Testament people who did not have faith were not saved. There is no difference. They are saved 'looking forward' to Messiah. We are saved 'looking back' to Messiah. His actual coming into time to complete his work was not required to be saved by faith in it because since God exists out of time, all that he planned was from eternity and effectual for salvation before he came. God saw Christ as being crucified before the creation of the world in the sense that whatever He planned in time is as creation as history.
But some might say, how did Abraham know about the Messiah. Well originally Messiah ws promised to Adam and Eve. God spoke to the serpent in front of them saying:
Later this promised seed from the woman, was promised to be the seed of Abraham, and Abraham had great faith in Messiah as he and his wife was beyond child bearing years. God said that this Messiah would cause all nations to obtain blessing from God, not just to his biological children:
We know for sure that Abraham has faith in Messiah. Even Jesus declared it:
So you see both Jew and Gentile, before and after Christ, can be saved by simple faith in Jesus for the forgiveness of our sins. Any humble person who acknowledge their need of forgiveness and hopes in Messiah will be saved and is a child of Abraham having the same faith as he had.
The answer to this question is yes, this is one of Gods great and wonderful mystery's.In the book of Romans 11:25-29 it says I do not want you to be ignorant of this mystery, brothers, so that you may not be conceited: Israel has experienced a hardening in part until the full number of the Gentiles has come in. And so all Israel will be saved. As far as the gospel is concerned, they are enemies on your account; but as far as election is concerned, they are loved on account of the patriarchs, for Gods gifts and his call are irrevocable. So basically God has hardened the hearts of the Jews to not except Jesus as there Savior, until all the people who are not Jews, Gentiles or Christians, except Jesus as there Savior that are going to.