How can one convince Sufi Muslim (Naqshbandi) friends in Germany that their path is wrong, and what are the arguments and evidence that can be presented to them in German?

The Naqshbandi tariqa (Sufi order) is a Sufi method that contradicts the Qur’an and Sunnah. It is characterized by many innovations (bid’ah), such as collective dhikr (remembrance of God) in one voice, dhikr using the singular name (Allah) and the third-person pronoun (Huwa - He), and seeking help from other than Allah, and requesting madad (spiritual support) from the dead. Furthermore, they have specific invocations that are not authenticated from the Prophet (peace be upon him). The Permanent Committee has ruled that Sufi orders, including the Naqshbandi, are innovative and misguided paths that involve major shirk (polytheism) due to their exaggeration concerning their shaykhs, seeking help from them, believing they have control over the universe, and their sayings such as: “He who has no shaykh, his shaykh is the devil,” and “He whom the discipline of the educator does not benefit, no book nor Sunnah will benefit him,” and “He who asks his shaykh: ‘Why?’, will never succeed.” All of these are false sayings. And whoever believes that their shaykhs bestow blessings, or benefit, or harm in matters that none but Allah can control, or that their obedience is absolutely obligatory even if they contradict the Qur’an and Sunnah, has committed major shirk that expels one from the fold of Islam. The Naqshbandi tariqa has foreign origins and includes the belief in Wahdat al-Wujud (unity of existence) and other heinous sayings, such as their claim that Allah takes the forms of animals in some instances of symbolic manifestation, and that reciting the Qur’an is the function of the intermediate ones, while prayer is the occupation of those who have reached the end.