Bismillah
Praise be to Allah, King of the Kings and Creator of all creations, prayer and peace be upon His Messenger Mohamed Ibn Abdullah.
Do they not then consider the Quran carefully?
To continue on the Ayah:" "Verily We: It is We Who have sent down the Reminder (i.e. the Qur'an) and surely, We will guard it (from corruption)." (Quran 15:9)
Sources of distortion in the previous books
In this context, we are not intending to abuse or attack sanctities of others, Allah may He be Glorified warned us against doing so even if those sanctities were idols.
“And insult not those whom they (disbelievers) worship besides Allah, lest they insult Allah wrongfully without knowledge” (Quran 6:108)
As for the people of the book, we accept their sanctities and hold them well respected. Actually Allah Commanded us not to argue with them except using a kind manner:
“And argue not with the People of the Scripture, unless it be in (a way) that is better (with good words and in good manner” (Quran 29:46)
Narrated under the authority of Abu Horaira that the Messenger salla Allah a`lyhee wa sallam said: Do not believer the people of the book neither accuse them of lying, but say we believe in what has been revealed to us and revealed to you, and our Ilah and you Ilah is one and to Him we are Muslimoun (submitters). (reported in Tafseer Tabari).