What is the ruling on a young man, a memorizer of the Quran and a student at an institute for recitations, who holds religious and worldly certificates, when asked about the distortion of the Quran, replied: "Allah knows best"? And what is the ruling on praying behind him? And is it permissible to inform people of this?

The assertion that the Qur’an has been distorted, or the endorsement or inward belief in such a distortion, constitutes disbelief (kufr). If a person is asked, "Do you believe that the existing Qur’an has been distorted?" and they respond, "I don't know," or "Allah knows best," they also disbelieve. There is no difference between asserting distortion and hesitating to deny it. Whoever belittles the Qur’an, or denies it, or distorts a letter or a verse from it, or rejects it or anything from it, or doubts any of that, is a disbeliever by the consensus of the people of knowledge. If proof is established against someone who hesitates to deny distortion, and they persist, knowingly and intentionally saying what they say, they have disbelieved, and prayer behind them is invalid. However, there is no need to inform people of their state if they do not declare their belief and are not a regular Imam. But if they declare this belief or are an Imam, one should warn against them after consulting with people of knowledge and virtue.