وَاللَّهُ يَشْهَدُ إِنَّ الْمُنَافِقِينَ لَكَاذِبُونَ
And Allah bears witness that the hypocrites are indeed liars. (Al-Munāfiqūn 63:1)
The hypocrites had said, إِنَّكَ لَرَسُولُ اللَّهِ — “You are surely the Messenger of Allah.” The proposition is true in itself, so why are they called liars? An argument for the belief-based definition points to their professing what they did not inwardly accept.
The source also reports responses to this argument. One must identify precisely which claim, testimony or act of profession is being evaluated.