Is it considered disbelief to doubt the disbelief of someone who uttered words of disbelief in jest, knowing that Allah is the Most Merciful of those who show mercy and that a person may utter a word of disbelief unintentionally, and would their good deeds then be rendered worthless?

Uttering disbelief jokingly indicates a disregard for religion and necessitates disbelief, unless the statement can bear both disbelief and other meanings. If the statement can bear both disbelief and other meanings, then a ruling of disbelief is not made unless the speaker intended disbelief, as stated in the jurisprudential rule: "If ninety-nine aspects point to the disbelief of a Muslim, and one aspect to keeping him in his Islam, then the mufti (definition) and judge should act upon that one aspect."

Disliking doubts and repelling them indicates faith, and whispers of disbelief are of no consequence because firmly established faith by certainty is not negated except by certainty. To overcome whispers of disbelief, it is advised to turn away from them and avoid dwelling on them, after seeking Allah's help.