Apostates and the mercy of Allah to those who repent 3:86-90
3:86 How shall Allah guide a people who lapse into disbelief after they believed and bore witness that the Messenger is true, and after receiving clear proofs! Allah does not guide the harm doers.
3:90 Indeed those who disbelieve after they have believed and increase in disbelief, their repentance shall not be accepted. These are those who are astray.