He does possess a will of his own and the capacity to choose; yet that will remains subordinate to the will of Allah, to His decree and predestination. For that very reason he is rewarded for obedience and punished for the sin he commits by his own choice and volition. As for the one who has no power of choice or intent—such as a person acting under duress, the forgetful, or the one physically incapable of carrying out an act of obedience—he is not punished, because his will and choice have been removed, whether through coercion, forgetfulness, incapacity, or loss of reason, as in the case of the insane or the feeble-minded. In these states he incurs no punishment for his actions, for he lacks both choice and will.
With regard to the two noble verses you mentioned, His saying, “You do not will except that Allah, Lord of all worlds, wills” (81:29) confirms what we have just explained. Allah affirms a will and choice for the servant, and He affirms a will for Himself, but He has made the servant’s will dependent on His own. Thus the verse establishes two wills: one for the servant and one for Allah—yet the servant’s will is subordinate to Allah’s.
As for His words, “Whoever wishes—let him believe; and whoever wishes—let him disbelieve” (18:29), this is not an offer of unrestricted choice. Rather, it is a rebuke, a warning, a threat. The continuation of the verse makes this clear: “Say, ‘The truth is from your Lord; so whoever wishes—let him believe, and whoever wishes—let him disbelieve. Indeed, We have prepared for the wrongdoers a Fire whose walls will surround them’” (18:29). The meaning is intimidation and censure: if a person disobeys Allah and disbelieves in Him, Allah will punish him, for he adopted disbelief by his own will and choice. He therefore deserves Allah’s punishment and entry into the Fire—“Indeed, We have prepared for the wrongdoers a Fire whose walls will encompass them” (18:29).