Is the principle "a person whose Islam has been established with certainty does not lose it except with certainty" confined to this worldly life? What if it becomes clear on the Day of Resurrection that what he did was an act of disbelief? And is repentance and uttering the Two Testimonies legislated for someone who fears that his action was an act of disbelief, in order to return to the certainty of Islam?

The rule "Whoever's Islam has been established with certainty, it cannot be removed except with certainty" is used to judge people and their dealings, such as marriage contracts and imamate. As for between a servant and his Lord, he can repent and seek forgiveness for what he knows and what he does not know, and for what is disbelief and what is less than it. Indeed, the Prophet, peace and blessings be upon him, guided Abu Bakr to a supplication that removes both minor and major shirk: "O Allah, I seek refuge in You from associating partners with You while I know, and I seek Your forgiveness for what I do not know."