Belief as a prerequisite for benefiting from revelation

هَـٰذَا بَصَـٰٓئِرُ لِلنَّاسِ وَهُدًى وَرَحْمَةٌ لِّقَوْمٍ يُوقِنُونَ

This [Qur’ān] is enlightenment for mankind and guidance and mercy for a people who are certain [in faith].