Is one excused by ignorance who says of himself that he is a disbeliever, while he does not know that this statement expels him from the fold of Islam?

Whoever intentionally and knowingly utters a statement of disbelief, understanding its meaning, exits Islam, even if he was jesting. The excusable ignorance is ignorance of the ruling and the meaning, not ignorance of the statement being disbelief. Whoever utters a word of disbelief jokingly or playfully disbelieves according to all scholars, and whoever utters it knowingly and intentionally disbelieves according to all scholars. However, whoever utters it by mistake or under duress does not disbelieve. The disagreement concerning one who utters it voluntarily but is ignorant of its being disbelief applies to expressions whose like is unknown to be disbelief, not to clear and explicit expressions. Jurists have explicitly stated that whoever utters a word of disbelief disbelieves, even if he did not intend its meaning, especially if he was jesting or playful. However, whoever utters a word of disbelief not knowing it is disbelief, then is informed of it and retracts it, is not ruled to be a disbeliever.