That key passage explains how Christians know that they are anointed ​ — holy spirit bears witness with their spirit.
فَعَلَى ضَوْءِ هٰذِهِ ٱلْآيَاتِ ،‏ يَعْرِفُ ٱلْمَمْسُوحُونَ أَنَّ رَجَاءَهُمْ سَمَاوِيٌّ لِأَنَّ ٱلرُّوحَ ٱلْقُدُسَ يَشْهَدُ مَعَ رُوحِهِمْ .‏