Sister, when it is mentioned Israel, then we have to take Israel literally. But when in scriptures the words like "believers, followers, etc" are mentioned then these can be any among us depending upon our deeds...
So when it is said that believers will be saved at the end..that does not mean that any one who will be born in a jew or christian or a muslim house will be considered as the believer.
As your bible has mentioned...
 I know that ye are Abraham's seed; but ye seek to kill me, because my word hath no place in you.
 I speak that which I have seen with my Father: and ye do that which ye have seen with your father.
 They answered and said unto him, Abraham is our father. Jesus saith unto them, If ye were Abraham's children, ye would do the works of Abraham.
 But now ye seek to kill me, a man that hath told you the truth, which I have heard of God: this did not Abraham.
 Ye do the deeds of your father. Then said they to him, We be not born of fornication; we have one Father, even God.
 Jesus said unto them, If God were your Father, ye would love me: for I proceeded forth and came from God; neither came I of myself, but he sent me.
 Why do ye not understand my speech? even because ye cannot hear my word.
 Ye are of your father the devil, and the lusts of your father ye will do. He was a murderer from the beginning, and abode not in the truth, because there is no truth in him. When he speaketh a lie, he speaketh of his own: for he is a liar, and the father of it.
So deeds will be the base which decide that who belongs to whom....It will never be decided upon the base of claim of a Rabbae or Priest or Imam....that you all are saved if you follow my interpretations or vice versa..
Israel is not only mentioned in your bible but in Quran too....That when the (end) time will come..we will collect you again back..
Why only Israel...only Allah knows best...but it seems that because they were the most beloved nation of its time...beloved by Allah...special food has been served for them from sky....for a very long period their matters were continuously in hands of Prophets...and many signs were shown to them...clearly..and everything was crystal clear for them.....yet they diverted following their desires..
so that is why they have been set as an example for all others...
So the nation of Israel is literal...the generations of those who were punished twice in their history as fullfillment of promise made to them...and still this coming back of them is again as per promise...and again if they stayed same (which they will..) ...the promise of punishment is valid again..and I think it is also mentioned in your bible..that who will come against whom in end times...
May Allah bless all
Allah knows best..
Ya Hayyo Ya Qayyum