Divine revelation and its certainty

الٓمٓر ۚ تِلْكَ ءَايَـٰتُ ٱلْكِتَـٰبِ ۗ وَٱلَّذِىٓ أُنزِلَ إِلَيْكَ مِن رَّبِّكَ ٱلْحَقُّ وَلَـٰكِنَّ أَكْثَرَ ٱلنَّاسِ لَا يُؤْمِنُونَ

Alif, Lām, Meem, Rā. These are the verses of the Book; and what has been revealed to you from your Lord is the truth, but most of the people do not believe.