The Quran states that the previous revelations were corrupted and no longer reliable.

The Quran presumes that the previous revelations, including the Bible, were available and authoritative during Muhammad's time. This is evident in various passages where Allah refers to the covenant made with the Children of Israel and the Christians, indicating that these groups were expected to uphold the teachings of the scriptures. If the Bible were truly corrupted, it would not make sense for the Quran to appeal to it for verification of Muhammad's prophetic claims. Furthermore, the Quran's acknowledgment of the Bible's existence suggests that it was considered a reliable source of divine revelation. Thus, the first Muslims believed in the authenticity of the Bible, using it to validate Muhammad's message, which ultimately leads to the conclusion that the Quran's assertion of corruption is self-defeating. In attacking the Bible, Muslims inadvertently undermine the Quran's own claims regarding the authority and preservation of previous scriptures.