What is the evidence of any distortion of the Bible?
Has there been any distortion introduced into the Quran?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu 'alyhi wa sallam, is His slave and Messenger.

The evidence of the distortion of the Bible and the Torah are countless and the following are the most important:

1-      The writers of the Gospels were not direct disciples of the Maseeh [‘Eesaa (Jesus) ].  Rather, they derived the Gospels from the atheist and pagan thoughts of Paul, and then attributed them to the Maseeh (Jesus) . This is supported by the fact that the four main Gospels (Matthew, Mark, Luke and John) were not known until early in the third century, and Arinos was the first one to mention these Gospels in 209 CE. Consequently, the Gospels and other Christian scriptures can never be trusted. 

2-      All throughout history, the Gospels were distorted and changed, to the extent that no version resembles another.  Muhammad Dhiyaa' Ad-Deen Al-A‘thami quoted that the process of writing began between 60 and 120 CE, then the written books were  exposed to mistakes in the process of copying them during the  proceeding two centuries. He added that these books may have been deliberately distorted in accordance with the creeds and aims of the sect to which the copier belonged.

3-      The Gospels imply blatant paganism, not to mention the radical differences among the various Christian sects regarding the divinity of the Maseeh .

With regards to the authenticity of the Quran and its preservation  against distortion, this is proven  by evidence, including: 

1-      There is only one existing version of the Quran.

2-      It was narrated from the Prophet, sallallaahu ‘alayhi wa sallam, in an absolutely authenticated method.

3-      It was written during the lifetime of the Prophet, sallallaahu ‘alayhi wa sallam

4-      The strongest evidence that the Quran is not (and will not be) distorted is that Allaah The Exalted challenged His creation to produce the likes of it; then He challenged them to produce ten chapters only and finally challenged them to produce even a single chapter. Today, this challenge remains open. If the Quran is fabricated, why can they not even produce a single chapter and defeat their enemy?

Allaah Knows best.