وَسُؤَالِ مُنْكَرٍ وَنَكِيرٍ فِي قَبْرِهِ عَنْ رَبِّهِ وَدِينِهِ وَنَبِيِّهِ
And the questioning by Munkar and Nakir in the grave about the person's Lord, religion and Prophet.
The questions concern three foundational matters:
Lord — whom did the person recognize as Lord?
Religion — what religion did the person follow?
Prophet — which Prophet did the person follow?
This is not an ordinary worldly examination; it concerns the reality of a person's faith.