culpability through knowledge

يَـٰٓأَهْلَ ٱلْكِتَـٰبِ لِمَ تَكْفُرُونَ بِـَٔايَـٰتِ ٱللَّهِ وَأَنتُمْ تَشْهَدُونَ

O People of the Scripture, why do you disbelieve in the verses of Allāh while you witness [to their truth]?