Shaikh ul-Islaam Ibn Taymiyyah said:
"And it is known by necessity in the Deen of the Muslims and by the agreement of all the Muslims that whoever follows a Shari'ah other than the Shari'ah of Muhammad then he is a disbelieves in some of the Book." Kaafir and it is like the Kufr of the one who believes in some of the Book and and disbelieves in some of the Book."
–"Al-Fataawa", Vol. 28/ 524
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Al-Haafidh Ibn Katheer said:
"So whoever leaves the clear Shari'ah, which was revealed to Muhammad Ibn Abdullah, the Seal of the Prophets, and takes the Hukm to other than it from the laws of Kufr which are abrogated, he has disbelieved. So what about the one who takes the Hukm to the 'Yasiq' (the law of the Tartars which mixed Shari'ah rulings with invented rulings) and puts it before it?! Whoever does that, he has disbelieved by the Ijmaa' of the Muslims."
– "Al-Bidaayah wa Nihaayah", Vol. 13/ 119
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Shaikh 'Abdul-'Azeez Ibn 'Abdullaah Ibn Baaz said:
"There is no Eemaan for the one who believes the laws of the people and their opinions are superior to the Hukm of Allah and His Messenger or that they are equal to it or that they resemble it or who leaves it or replaces it with fabricated laws and institutions invented by people, even if he believes that the laws of Allah are more encompassing and more just."
– "Risaalat Wujoob Tah'keem Sharee'at Allah' Pg. 39, which follows the "Risaalat Tah'keem Al-Qawaneen" Published by "Daar Al-Muslim"
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Shaikh Muhammad Ibn Saalih al-'Uthaymeen said:
"The first type is when the Hukm of Allah is removed and replaced with another Taghuutee Hukm, so that the Hukm of the Shari'ah is eliminated between the people and he puts in its place another Hukm from the fabrication of the humans and they remove the laws of the Shari'ah concerning the Mu'amalah (i. e. the general actions between people) and they put in its place fabricated laws and this, without doubt, is Istib'daal (i. e. replacement) of the Shari'ah of Allah subhaanahuu wa-ta'ala, with other than it. And this is Kufr which removes one from the Milla because this person put himself at the level of the Creator because he shara'a (legislated) for the slaves of Allah that which Allah ta'ala did not give permission for and that is Shirk in His, ta'ala's saying:
"Or have they partners with Allâh (false gods), who have instituted for them a religion, which Allâh has not allowed?" (Ash-Shu'ara, 21)
– "Fiqh Al-'Ebaadaat", #60
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Shaikh Muhammad Naasiruddin Al-Albaanee:
Who said, in one of his earlier cassette recorded lessons, wherein he is describing an argument he had with someone about the Takfeer of Mustafa Ataturk, the secularist who converted the constitution of Turkey from the Hanafee code Shari'ah, to the man-made laws. So Shaykh Al-Albaanee said:"I made clear to him (i.e. his opponent) that the Muslims did not make Takfeer to Ataturk who was Muslim. No. (They did so) when he freed himself from Islaam when he implicated upon the Muslims an institution other than the institution of Islaam. And from that was the example of his equalizing between the inheritance of the male and the female. But Allah says according to us, 'And for the male is the share of two females. ' And then he obligated upon the Turkish masses, the Qobah (i. e. a Turkish-style hat)."– "Fataawa Ash-Shaykh al-Albaanee wa-Maqara'netihah bi'Fatawaa Al-'Ulaama", Pg. 263 from his cassette #171.
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