Muslims believe in Holy Bible,Muslims believe that it was once revealed by Allah.It is the part of our faith to believe in it.
Say, [O believers], “We have believed in Allah and what has been revealed to us and what has been revealed to Abraham and Ishmael and Isaac and Jacob and the Descendants and what was given to Moses and Jesus and what was given to the prophets from their Lord. We make no distinction between any of them, and we are Muslims [in submission] to Him.”(2:136)
And who believe in what has been revealed to you, [O Muhammad], and what was revealed before you, and of the Hereafter they are certain [in faith].(2:4)
The Books were revealed by Allah,we must believe that but it is also mentioned that we should know they are changed now:
Sahih Bukhari, Volume 9, Book 92, Number 461:
Narrated Ubaidullah: Ibn ‘Abbas said, “Why do you ask the people of the scripture about anything while your Book (Quran) which has been revealed to Allah’s Apostle is newer and the latest? You read it pure, undistorted and unchanged, and Allah has told you that the people of the scripture (Jews and Christians) changed their scripture and distorted it, and wrote the scripture with their own hands and said, ‘It is from Allah,’ to sell it for a little gain. Does not the knowledge which has come to you prevent you from asking them about anything? No, by Allah, we have never seen any man from them asking you regarding what has been revealed to you!” (Sahih Bukhari, Volume 9, Book 92, Number 461)
Narrated Abu Huraira:
The people of the Scripture (Jews) used to recite the Torah in Hebrew and they used to explain it in Arabic to the Muslims. On that Allah’s Apostle said, “Do not believe the people of the Scripture or disbelieve them, but say:– “We believe in Allah and what is revealed to us.” (2.136) Sahih Bukhari Volume 6, Book 60, Number 12
Some Non Muslims do not believe that bible is changed,but the fact is that It was changed intentionally as well as unintentionally.
Causes of the Corruption of the Traditional Text of the Holy Gospels
by John William Burgon and Edward Miller
Some Non Muslims are confused about the verses that there is no change in the words of Allah,so how could the Bible change?
The answer is simply that the verses are about the promises of Allah,the verses were not about the preservation of previous scriptures.See 10:64