A hesitant listener might say, “Perhaps the messenger has arrived,” while a denier asserts, “The messenger definitely did not arrive.” The first case involves uncertainty and the second direct rejection; they need not call for identical responses.
إِنَّ الرَّسُولَ قَدْ وَصَلَ.
The messenger has indeed arrived.
The statement strengthens the proposition against doubt. But how much reinforcement best answers active denial depends on its intensity and available evidence. Merely counting emphatic particles is not a sufficient rhetorical analysis.