The ruling on one who criticizes slavery and its legitimacy

Question:
He says: Honorable Shaykh, may Allah grant you success, if someone criticizes slavery and its legitimacy, is he immediately declared a disbeliever, or must we establish the proof against him?

Answer:
If he is ignorant, it is explained to him, especially since some of the Islamic writers, as they call themselves, write such things and say that Islam compromised regarding slavery, and that otherwise it does not approve of it, but rather it compromised in it. Or they say that in contrast, because the disbelievers enslave Muslims, Islam enslaves them by way of reciprocity, or such empty talk. And this, unfortunately, exists in *In the Shade of the Qur'an* by Sayyid Qutb. This statement exists, and it is a false statement. So the one who says this, if he is ignorant, it is explained to him. And if he is knowledgeable and says, "No, I do not accept this," then he apostatizes from the religion of Islam. Yes.