كَلَّا بَلْ تُكَذِّبُونَ بِٱلدِّينِ
Sentence structure
كَلَّا rejects the preceding attitude and بَلْ shifts to the real fault. تُكَذِّبُونَ is the verb with attached wāw as subject; بِٱلدِّينِ is linked to it.
Ayah summary
The underlying error is that people deny the Day of Recompense and accountability.
كَلَّا — Nay
Grammar: A deterrent and rebuking particle.
بَلْ — But
Grammar: A transition particle shifting to the real fault.
تُكَذِّبُونَ — you deny
Grammar: A Form II second-person masculine plural imperfect of the five verbs. The penultimate و is the subject and final ن marks the indicative.
بِٱلدِّينِ — the Judgment
Grammar: بِ is a preposition, ٱلْ the definite article, and دِّينِ the genitive noun; the phrase is linked to تُكَذِّبُونَ.