It was also God, through Paul (Bible is inspired) explaining how things work. Israel/the Jews rejected the Messiah, so do to this "disobedience" the gospel went out to the Gentiles. The Gentiles responded with "obedience", and accepted Christ. (The Gentiles who believed and joined the church.) Israel is under a partial hardening (and it is wrtiten in such a way to know that the purpose you have given is not the purpose, but only part of it) until the fulness of the Gentiles come in. What does that mean? That means that Israel as a whole will not be saved until the fulness of the Gentiles has come in. Then everything comes around full circle, and because of the obedience of the Gentiles, God will have mercy on Israel, and Israel will become obedient again, and, as Paul says "all Israel will be saved." Now, the way I believe it works, it is all Israel that is saved. All Israel that survives the Great Tribulation. (Which won't be much. Zechariah says that it is only 1/3rd of the population at the time. The other 2/3rd... perish right then.
When all is said and done, and it comes to the salvation of Israel, only the remnant still remains, everyone else has perished. Which is why Paul can say "all Israel will be saved." Only the remnant is alive to be saved.
The argument is not that Jews have lost their chance to be justified, but that God has not rejected the Jews. That is, they are still people of the covenant, still God's chosen people. While all Jews fit under God's chosen people as the nation in which God placed His name, not all are saved. Many rejected God. The remnant has not accepted Jesus, but they haven't rejected God. In the end, they will see Jesus for who He is, and accept Him.
Absolutely. God is not done with Israel. 1948 is a part of the last days. It is also the completion of prophecies God made of an exile/diaspora of Jews. Someone did the calculations using the Leviticus principle, and when they calculated out the dates, it ended in 1948. I don't accept that blindly, however, it doesn't go against my beliefs so it is not simply thrown away, but there for thought and reflection on God. There are a few of these supposed perfectly fitting prophecies that could be mistakes made in calculations, or a lot of assumptions that make it work. So... in the end, more of a curiosity.