Except for sacred books for religions born after recent times (the Book of Mormon, the Book of the Unification Church), there is no reason for them to be categorized as gisho regardless of whether or not they included falsehoods.
近世以降に派生した宗教の教典（モルモン書、世界基督教統一神霊協会）などを除けば、来歴に虚偽を含んでいようと、殊更に偽書呼ばわりされることはない。