What are the conditions for the one who establishes the proof against one who has fallen into major shirk (associating partners with Allah)?
Machine translationRead the Arabic original
The questioner : Regarding the one who falls into major shirk, prompted by scholars of evil, without knowing that it is major shirk, he needs a fatwa (scholarly legal ruling) to be established. What is required of the one who establishes this proof by which he is declared a disbeliever?
The Shaykh : The condition is that he must be well-versed in the Book and the Sunnah. Of course, only what?
The questioner : Authority. He does not need to hold authority. No.
The Shaykh : This is a matter of knowledge. It is not required that the one ruling be a judge, but rather that he be a scholar, because the proof of Allah is established by explanation, not by swords. Therefore, among the etiquette of Islam before fighting is presenting the proof and explanation, and then fighting follows. So, it is only required that he be knowledgeable of the Book and the Sunnah.
The Shaykh : The condition is that he must be well-versed in the Book and the Sunnah. Of course, only what?
The questioner : Authority. He does not need to hold authority. No.
The Shaykh : This is a matter of knowledge. It is not required that the one ruling be a judge, but rather that he be a scholar, because the proof of Allah is established by explanation, not by swords. Therefore, among the etiquette of Islam before fighting is presenting the proof and explanation, and then fighting follows. So, it is only required that he be knowledgeable of the Book and the Sunnah.
Source
سلسلة الهدى والنور، رقم 1885 في قناة «تسجيلات الإمام الألباني - محمد أبو ليلى الأثري» — youtube.com (1:50)
The Arabic text is a machine transcription of the audio recording.