I was asked this by an Apostate. He wanted to know what the evidence is that an Apostate can evade execution by repenting and returning to Islam.
I know this is the judgement of the madhahib and Umar ra did this with the Iraqi apostates but this did not satisfy him.
Is there any evidence from Quran or Sunnah that the apostate is permitted to return to Islam and thus avoid execution?
Verses about Allah being all merciful are important but in this case I am not sure if they are evidence the Apostate should be able to evade execution, perhaps it would mean Allah has forgiven the Apostate on the basis of his execution being the expiation, so his Repentance would help him from the punishment of the Afterlife but not from the legal penalty, just as a thief cannot escape the penalty for theft by repenting. On the other hand, it could also be argued that the victim of theft can waive the penalty for the thief, and Apostasy which is a crime against Allah can also be waived by Allah.
Because of this uncertainty, I would prefer it if the answers did not invoke Allah’s mercy as the proof an Apostate can escape his penalty by repentance unless they can prove these verses can be applied to waiving the apostasy penalty.