إِنَّ الَّذِينَ تَرَوْنَهُمْ إِخْوَانَكُمْ
Those whom you regard as your brothers ...
A relative clause can bring a hearer’s mistaken assumption into focus. By mentioning the identifying description, the speaker exposes the very belief that the following statement challenges.
Calling attention to an error comes from the contrast between the listener’s assumption and the reality the utterance presents; the mere presence of «الذين» does not by itself signal a mistake.