Praise be to Allah, and peace and blessings be upon the Messenger of Allah.
Taʿṭīl, in principle, means denial and negation. One of its forms is for a person to deny the existence of Allah, or to deny His Names and Attributes that He has affirmed for Himself.
In this sense, taʿṭīl is closer to kufr, because denying the existence of Allah or denying what is established for Him is contrary to the foundation of faith in Allah.
Nevertheless, the terms kufr and shirk may sometimes be used interchangeably, depending on the context.
An example is the story of the owner of the two gardens in Surat al-Kahf. He denied the Resurrection, so his companion said to him:
“Have you disbelieved in Him who created you from dust, then from a sperm-drop, then proportioned you as a man?”
Then, after his garden was destroyed, the man said:
“I wish I had not associated anyone with my Lord.”
Thus, his position was described in the verses once as kufr and once as shirk, indicating that the two terms may overlap in certain usages.
Imam al-Nawawi, may Allah have mercy on him, said:
“Shirk and kufr may be used with the same meaning, namely disbelief in Allah Most High. They may also be distinguished, with shirk being specifically applied to worshipping idols and other created beings while acknowledging Allah Most High; in that case, kufr is broader than shirk.”
Accordingly, kufr is broader in some scholarly usages, while shirk may sometimes be used in a more specific sense, and it may also be used to refer to disbelief in Allah as a form of emphasis.
Ibn al-Qayyim, may Allah have mercy on him, stated that shirk can relate to the essence of the one being worshipped, His Names and Attributes, and His Actions, just as it can relate to worshipping and dealing with Him.
He mentioned among the forms of shirk related to Allah “the shirk of taʿṭīl”, giving Pharaoh as an example, when he said:
“And what is the Lord of the worlds?”
Allah also relates his words:
“And Pharaoh said, ‘O Haman, construct for me a tower that perhaps I may reach the ways— the ways of the heavens—so that I may look at the God of Moses; but indeed, I think him to be a liar.’” [Ghafir 40:36–37]
Ibn al-Qayyim's point is that taʿṭīl and shirk may meet in the sense that whoever denies Allah's Names and Attributes, or denies the rights due to His Oneness, has deviated from the reality of tawhid.
He explained that taʿṭīl can take several forms, including:
For this reason, some scholars used the term “the shirk of taʿṭīl”, because taʿṭīl contradicts the foundation of tawhid or one of its aspects.
A distinction must be made between describing a statement or belief and judging a particular individual.
A particular statement may itself be one of the statements of kufr or shirk, while judging a specific person requires consideration of his circumstances, whether the proof has been established against him, his knowledge and intention, and other matters that should be referred to qualified scholars.
Taʿṭīl is also not of one single degree. Some forms involve denying the existence of Allah, while others involve denying some of His Names and Attributes. Each form has its own ruling and detailed discussion among scholars.
Taʿṭīl means denial and negation, and it may refer to denying the existence of Allah, denying His Names and Attributes, or denying His rights to worship.
In principle, it is closer to kufr, because kufr is broader than shirk in some scholarly terminology.
Nevertheless, some scholars have called taʿṭīl “the shirk of taʿṭīl”, because it contradicts tawhid and negates one of its aspects.
Therefore, there is no contradiction between describing taʿṭīl as kufr and calling it shirk in some scholarly works, because the terms kufr and shirk may overlap in usage, while there remains a distinction between them in technical terminology.
And Allah knows best.