Will Christians be saved?
And nearest among them in love to the believers [the Muslims] wilt thou find those who say “we are Christians” because amongst these are men devoted to learning and men who have renounced the world, and they are not arrogant” (Surat Al-Maidah 5:82).
We sent after them Jesus the son of Mary, and bestowed on him the Gospel; and we ordained in the hearts of those who followed him compassion and mercy (Surat Al-Hadid 57:27).
We did aforetime grant to the children of Israel the Book, the power of command, and prophethood; We gave them, for sustenance, things good and pure; and We favoured them above all nations (Surat Al-Jathiyah 45:16).
Muhammad’s attitude towards the Christians completely turned at a later stage.
YUSUFALI: O ye who believe! take not the Jews and the Christians for your friends and protectors: They are but friends and protectors to each other. And he amongst you that turns to them (for friendship) is of them. Verily Allah guideth not a people unjust.
PICKTHAL: O ye who believe! Take not the Jews and the Christians for friends. They are friends one to another. He among you who taketh them for friends is (one) of them. Lo! Allah guideth not wrongdoing folk.
The Christians’ attitude towards Muhammad had always been the same; they never accepted him as one of their prophets. If God had revealed the Quran, would he not have known that the Christians would not end up accepting Muhammad? Then why were there praises of Christians?
On the other hand, Muhammad did not know the Christians would never accept him. That was why he started off with praises for them and later turn 180% around and speak against them when it became clear that they would not accept him.
Will the Jews be saved?
This verse says that those who follow the Jewish scriptures are saved.
Those who believe [in the Koran] and those who follow the Jewish [Scriptures] and the Christians and the Sabians, any who believe in Allah and the last days, and work righteousness, shall have their reward with their Lord, on them shall be no fear, nor shall they grieve (Surat Al-Baqarah 2:62).
This verse says that Jews are not saved because of their wrong doctrines eg calling Uzair (Ezra) son of God.
The Jews call Uzair a son of Allah, and the Christians call Christ the son of Allah. That is a saying from their mouth; [in this] they but imitate what the infidels (literal translation) of old used to say. Allah’s curse be on them: how they are deluded away from the truth (Surat Al-Tawbah 9:30).