There is no Salvation Except through Faith in the Qur'an
Allah says:
قل
say:
Allah says: O Muhammad, say,
يا أهل الكتاب لستم على شيء
O People of the Scripture! You have nothing...,
meaning no real religion,
حتى تقيموا التوراة واﻻنجيل وما أنزل إليكم من ربكم
...till you act according to the Tawrah, the Injil, and what has (now) been sent down to you from your Lord (the Qur'an).''
until you adhere to and implement the Tawrah and the Injil. That is, until you believe in all the Books that you have that Allah revealed to the Prophets. These Books command following Muhammad and believing in his prophecy, all the while adhering to his Law.
Allah's statement,
وليزيدن كثيرا منهم ما أنزل إليك من ربك طغيانا وكفرا
Verily, the revelation that has come to you from your Lord makes many of them increase in rebellion and disbelief.
فﻼ تٲس على القوم الكافرين
So do not grieve for the people who disbelieve,
Do not be sad or taken aback by their disbelief.
Allah said next,