فَمَنْ يَعْمَلْ مِثْقَالَ ذَرَّةٍ خَيْرًا يَرَهُ
Whoever does an atom's weight of good will see it. (Al-Zalzalah 99:7)
The argument treats faith itself as a genuine good. If a believer were punished forever with no beneficial result from faith, applying this universal promise would become difficult.
An objection holds that reward might be received before punishment or through another benefit. The reply brings in the promise of enduring Paradise for believers, rather than assuming that a brief benefit completely exhausts faith's reward.