"Then when He wills, He will resurrect him," meaning He will bring him back to life. This refers to the Resurrection; that is, how can he disbelieve? This is like His saying: "How can you disbelieve in Allah when you were lifeless (dead) and He brought you to life?" (up to the end of the verse).
﴿ثمَّ إِذا شَاءَ أنشره﴾ أَحْيَاهُ؛ يَعْنِي: الْبَعْثَ؛ أَيْ: كَيْفَ يَكْفُرُ؟! كَقَوْلِهِ: ﴿كَيْفَ تَكْفُرُونَ بِاللَّهِ وكنتم أَمْوَاتًا﴾ الْآيَةَ.
