Do all Jews and Christians go to the Hell-Fire?>Why should not a Christian or a Jew go to Paradise when he/she>believes in oneness of GOD and do righteous deeds (but doesn't believe>Mohammed (PBUH) as Prophet)? Where in Quern Allah did mention that ONLY>Muslim (who believes in oneness of GOD and Mohammed as Prophet) will go>to Paradise? What about the verse (2:63)?
Praise be to Allah,
First of all, Neither Christians nor Jews (in general) believe in oneness of Allah. On time, A Christian man entered the mosque while the messenger of Allah (pbuh) was reciting from the Qur'aan:
They (Jews and Christians) took their rabbis and their priests to be their lords besides Allâh (Qur'aan 9:31)
So he said: "We did not worship our priests." The Messenger said: "Yes, you do. Don't they make the Halal (allowed matters) Haram (disallowed matters) and the Haram Halal, then you follow them?" He answered yes. The Messenger said: "That is worshiping them."
So by obeying their priests in things which they made lawful or unlawful according to their own desires without being ordered by Allâh, they made them partners of Allâh.
But suppose that one of them does not do so, he believes in the oneness of Allah but does not believe with his messenger or he refuse to be Muslims. In this case he will be Kafir (disbeliever) too since he refused to believe with what Allah has sent. The following verses talks about that:
Truly, the religion with Allâh is Islâm. Those who were given the Scripture (Jews and Christians) did not differ except, out of mutual jealousy, after knowledge had come to them. And whoever disbelieves in the Ayât (proofs, evidences, verses, signs, revelations, etc.) of Allâh, then surely, Allâh is Swift in calling to account. (Qur'aan 3:19)
 Those who disbelieve from among the people of the Scripture (Jews and Christians) and among Pagans, were not going to leave (their disbelief) until there came to them clear evidence.
 A Messenger (Muhammad) from Allâh, reciting (the Qur'ân) purified pages.
 Containing correct and straight laws from Allâh.
 And the people of the Scripture (Jews and Christians) differed not until after there came to them clear evidence. (i.e. Prophet Muhammad (Peace be upon him) and whatever was revealed to him).
 And they were commanded not, but that they should worship Allâh, and worship none but Him Alone (abstaining from ascribing partners to Him), and perform Prayers and give Charity: and that is the right religion.
 Verily, those who disbelieve (in the religion of Islâm, the Qur'ân and Prophet Muhammad (pbuh)) from among the people of the Scripture (Jews and Christians) and pagans will abide in the Fire of Hell. They are the worst of creatures.
 Verily, those who believe [in the Oneness of Allâh, and in His Messenger Muhammad (pbuh)) including all obligations ordered by Islâm] and do righteous good deeds, they are the best of creatures.
 Their reward with their Lord is Eden Paradise (Gardens of Eternity), underneath which rivers flow, they will abide therein forever, Allâh Well-Pleased with them, and they with Him. That is for him who fears his Lord.
You also can use many Hadiths that insure 100% that every Christian or Jew who hear about Muhammad (pbuh) then does not follow him, he will go to the hell-fire. However this person will not stay in the hell-fire forever. The Messenger of Allah (pbuh) said:
"By the One in Whose hand is the soul of Muhammad, there is no-one of this Ummah, Jew or Christian, who hears of me then dies without believing in that with which I have been sent, but he will be one of the people of Hell." (Sahih Muslim, 153).
As for the verse (2:63), it was revealed when Salman al-Farisi (r.a) asked the prophet (pbuh) about his friends who died before they meet Muhammad (pbuh)... So, the meaning is that Jews had to follow the Torah until the Injil was revealed. After that, Jews had to follow the Injil until the Quran was revealed. After that, they had to follow the Quran as in (3:85).
 And whoever seeks a religion other than Islâm, it will NEVER be accepted of him, and in the Hereafter he will be one of the losers.  How shall Allâh guide a people who disbelieved after their belief and after they bore witness that the Messenger (Muhammad SAW) is true and after clear proofs had come unto them? And Allâh guides not the people who are Zâliműn (polytheists and wrongdoers).  They are those whose recompense is that on them (rests) the Curse of Allâh, of the angels, and of all mankind.  They will abide therein (Hell). Neither will their torment be lightened, nor will it be delayed or postponed (for a while). (Qur’an 3:85-88)