Shaykh Ahmad Baazmool said, “Al-Bidah al-Mufassiqah is the [innovation] that doesn’t make the person who performs it leave the religion, like the bidah (innovation) of Al-Ashaa‘irah [who deny the majority of Allahs names and attributes], and Al-Murji’ah [who hold incorrectly that iman (faith) does not increase with good deeds or decrease with sins] and the likes.
As for Al-Bidah Al-Mukaffirah, then the person who performs it falls into one of the nawaaqid (nullifiers) of the religion, like the statement of Al-Jahmiyyah that the Qur’aan is created, and like the statement of Al-Ittihaadiyyah and Al-Hulooliyyah that Allaah incarnates and unites in His creation or that the whole existence united and appeared in Allaah, the Mighty and Majestic. These are beliefs of kufr (disbelief), while notifying about that which the Scholars notified about: that this is a general ruling, and applying this ruling requires returning to the Scholars and their implementation.
Applying it [the ruling that a person has fallen into Al-Bidah Al-Mukaffirah] requires returning to the scholars, and they look to the circumstances of the issue and the ruling on each individual according to what the principles of the sharee’ah necessitate…
Another [way of looking at] Al-Bidah Al-Mufassiqah [is that it] means – according the scholars – that the innovators are not saalihoon (pious, righteous people), rather they are fasaqah (disobedient, rebellious people) from the wicked fussaaq (disobedient, rebellious people). This is why some people say to you, “So and so is a person of innovation, but he is saalih (righteous) and Taqiy (Godfearing).” We say to you, “You are wrong! As long as he is an innovator, he fell into innovation and the scholars declared him an innovator, then he is faasiq (disobedient, rebellious).”” Ref: Questions And Answers regarding Manhaj By Shaykh Ahmad Baazmool
Posted By Abdul Kareem Ibn Ozzie