BELIEVE - ISLAMIC (Questions/Answers)

Q: About The REVELATIONS (Holy books, Bible ,torah, Injil ,Al-Quran)?

Muhammad sallallaho alaihey wa sallam, didn't wrote the Quran, He Recited the Holy Verses as Allah(God) revels upon Him,
then the sahabas(companions) of Prophet Muhammad sallallaho alahey wa sallam,
write those verses as Pages by pages ,

as  in Quran mentioned : 
“And those who disbelieve say: Why is not the Quran revealed to him all at once? Thus (it is sent down in parts), that We may strengthen your heart thereby. And We have revealed it to you gradually, in stages”
Quran (Surah Al-Furqan Verse 32)

And in another Surahas,

(Surah Zumar),👇
41. We sent down upon you the Book for mankind in truth. He who follows guidance does so for the good of his soul. And he who strays in error does so to its detriment. You are not their overseer.

(surah Sajdah)👇
2. The revelation of the Book, without a doubt, is from the Lord of the Universe.
3. Yet they say, “He made it up.” In fact, it is the Truth from your Lord, to warn a people who received no warner before you, that they may be guided.

-------------------------------

Now ..
bible was not in original form, but few verses still lefted,  As Allah(God) has mentioned,
"And We sent, following in their footsteps, Jesus, the son of Mary, confirming that which came before him in the Torah; and We gave him the Gospel, in which was guidance and light and confirming that which preceded it of the Torah as guidance and instruction for the righteous. (Al-Maeda 5:46, English - Sahih International)

And let the People of the Gospel judge by what Allah has revealed therein. And whoever does not judge by what Allah has revealed - then it is those who are the defiantly disobedient.
(Al-Maeda 5:47, English - Sahih International)

And We have revealed to you, [O Muhammad], the Book in truth, confirming that which preceded it of the Scripture and as a criterion over it. So judge between them by what Allah has revealed and do not follow their inclinations away from what has come to you of the truth. To each of you We prescribed a law and a method. Had Allah willed, He would have made you one nation [united in religion], but [He intended] to test you in what He has given you; so race to [all that is] good. To Allah is your return all together, and He will [then] inform you concerning that over which you used to differ.
(Al-Maeda 5:48, English - Sahih International)

And if only the People of the Scripture had believed and feared Allah, We would have removed from them their misdeeds and admitted them to Gardens of Pleasure.
(Al-Maeda 5:65, English - Sahih International)

And if only they upheld [the law of] the Torah, the Gospel, and what has been revealed to them from their Lord, they would have consumed [provision] from above them and from beneath their feet. Among them are a moderate community, but many of them - evil is that which they do.
(Al-Maeda 5:66, English - Sahih International)

O Messenger, announce that which has been revealed to you from your Lord, and if you do not, then you have not conveyed His message. And Allah will protect you from the people. Indeed, Allah does not guide the disbelieving people.
(Al-Maeda 5:67, English - Sahih International)

Say, "O People of the Scripture, you are [standing] on nothing until you uphold [the law of] the Torah, the Gospel, and what has been revealed to you from your Lord." And that which has been revealed to you from your Lord will surely increase many of them in transgression and disbelief. So do not grieve over the disbelieving people.
(Al-Maeda 5:68, English - Sahih International)

Indeed, those who have believed [in Prophet Muhammad] and those [before Him] who were Jews or Sabeans or Christians - those [among them] who believed in Allah and the Last Day and did righteousness - no fear will there be concerning them, nor will they grieve.
(Al-Maeda 5:69, English - Sahih International)