Shaykh Ibn Baz (rahimahullaah) stated in a fatwa in response to a question about the effect of magic (as occurs here) the following:

فدل على أنه خلاف التقوى وخلاف الإيمان ، وبين أيضاً أنه كفر قال: وَمَا يُعَلِّمَانِ مِنْ أَحَدٍ حَتَّى يَقُولاَ إِنَّمَا نَحْنُ فِتْنَةٌ فَلاَ تَكْفُرْ, فدل على أن تعلم السحر وتعليم السحر واستعماله كفر بعد الإيمان نعوذ بالله؛ لأنه إنما يكون بطاعة الشياطين وعبادتهم من دون الله, فإذا أطاع الشياطين من الجن وعبدهم من دون الله علموه بعض الأشياء التي تضر الناس, ويروى عن أبي هريرة - رضي الله عنه - عن النبي - صلى الله عليه وسلم - قال: (من سَحَرَ فقد أشرك), فالمقصود أن السحر من أسباب الشرك؛ لأنه لا يتوصل إليه إلا بعبادة الجن, والاستغاثة بهم, والاستعانة بهم, والتقرب إليهم بذبح, أو نذر, أو سجود, أو غير ذلك, فلهذا حكم العلماء على السحرة بأنهم كفار هذا هو المعروف عند جمهور أهل العلم أن كل ساحر كافر, ...... السحر فهو كافر, قال بعض أهل العلم يسأل عن صفة السحر إن وصف شيئاً يدل على كفره صار كافراً وإلا صار من جملة المعاصي ومن جملة الظلم للناس, وبكل حال هذا المعنى ما يخالف ما قاله الجمهور فإن مراد الجمهور هو السحر الذي لا يعرف له أسباب تبعده عن الكفر, فالساحر في الغالب إنما يكون ساحراً بخدمته للجن وعبادته للجن, أما إذا ادعى سحراً في شيء لا يكون من جنس السحر ولكنه قد يضر الناس بعمل آخر غير عبادة الجن وخدمت الجن, وطاعتهم, والاستغاثة ونحو ذلك كأشياء يستعملها من مواد تؤكل, أو تشرب, أو يدخن بها, أو يدهن بها فتضر بعض الناس هذا, من باب الضرر من باب الظلم, من باب الإيذاء ليس من باب عبادة الجن. بارك الله فيكم

The translation of which is:

So this indicates that it (magic) is in opposition to piety (taqwa) and in opposition to faith (eemaan) and explains also that it is disbelief (kufr), He (Allaah) said, "And they (the two Angels) did not teach anyone until they said, 'Verily we are a tribulation, so do not disbelieve'." (2:102) So this indicates that learning magic, teaching magic and employing magic is disbelief after faith, we seek refuge in Allaah.

This is because it (the magic) occurs by obedience to the devils and worship of them besides Allaah. So when he obeys the devils amongst the Jinn, and worships them besides Allaah, they teach him some things that harm the people, and it is reported from Abu Hurairah (radiallaahu anhu) from the Prophet (sallallaahu alayhi wasallam) that he said, "Whoever practised magic has committed shirk", and the intent is that magic has causes which (involve) shirk, because (effecting) magic cannot be attained except by worshipping the Jinn, seeking rescue and aid from them, and seeking nearness to them by sacrificing or making oath or prostration or other than that.

For this reason, the Scholars have judged that the magicians are disbelievers, this is what is known to the majority of the people of knowledge that every magician is a disbeliever [some missing text] magic, then he is a disbeliever. Some people of knowledge said that he (the magician) is asked to describe his magic and if he describes anything which indicates his disbelief, he becomes a disbeliever, otherwise it becomes from the generality of disobedience and from the generality of oppressing the people. But in any case this meaning (i.e. this clarification) does not oppose what the majority have said, because the intent of the majority is [to refer to] that magic for which there are no known reasons that make it remote from being kufr. The magician overwhelmingly is a magician due to his service to the Jinn and his worship of the Jinn.

As for when he claims to have done magic in a matter but which is not from the type of magic [being spoken of involving the Jinn] but he harms the people by some other works which do not involve worship of the Jinn and service to the Jinn, obedience to them and seeking rescue (aid) from them and what is like that such as the use of things (materials) which are eaten or drunk, or which have been fumigated or oiled and which people are then harmed by, this is from the angle of causing harm and oppression, from the angle of causing harm, it is not from the angle of worshipping the Jinn. May Allaah bless you.