The surah opens not with an answer but with a question put to you: "About what are they asking one another?" (78:1) — and the answer it gives back is "the great news" (78:2), the report of the Resurrection and the Day of Judgment, the one matter "concerning which they are in disagreement" (78:3). It is honest about that disagreement. In Mecca some affirmed the news and many flatly denied it; and if you stand outside faith today, you may feel you belong with the deniers — the claim that the dead are raised and called to account can sound like the least believable thing a book could ask you to accept. The surah grants you that. But notice what it does instead of arguing: it does not begin by silencing the doubt, it begins by drawing the doubter in, as if to say the news is too great to leave you merely a bystander. And the question it overhears in Mecca is not an old dispute you are reading about — it is the question every human being already lives under. Is this life all there is? Are you answerable for it? You ask that question precisely because some part of you already half-knows the answer; the heart does not disagree about whether it matters that it will end, only about whether it dares to say so. That recognition is not something the surah installs in you — it finds it already there. The One who raises the question is the One who can answer it, and He is asking it of you.
These two verses answer those who dispute and doubt the resurrection and the great news of the Hereafter. The word "Kallā" ("No indeed!") cuts cleanly through their denial, and the warning "they will come to know" — repeated and intensified with "Then again" — carries an unshakeable divine certainty: what they reject will one day stand before them, undeniable. But the same certainty that unsettles the one who turns away is a quiet reassurance for you. That instinct in you — that a reckoning is fitting, that the good and the wrong of a life cannot simply dissolve to nothing — is not naïveté; it is the recognition God set in you that justice must finally be real. The doubling of the warning is the patience of a Lord who would rather you come to know this now, with your heart open, than be overtaken by it later — which is why the same sūrah ends not on a threat but an open door: "so whoever wills, let him take a way of return to his Lord" (78:39). He is telling you plainly where it leads, while the road is still ahead of you to walk.