The Imaam said, “And it has reached the extent that one of those factions [hizbs] made it obligatory on all its members to adopt any opinion the hizb adopts, whatever that opinion maybe–even if it has no value from an Islamic point of view–and if that individual is not convinced with a particular opinion of the hizb, he is excommunicated and is not regarded as being part of the hizb, [a hizb] which calls itself a [so called], ‘Islamic’ one.
And what that means is that they are going back to what resembles the Jews and the Christians when they follow whatever their rabbis and monks make halaal or haram, for indeed Allaah, the Most High, has said, “They have taken their rabbis and monks as lords besides Allaah and [also] the Messiah, the son of Mary. And they were not commanded except to worship one God–there is no deity [who has the right to be worshipped] except Him. Exalted is He above whatever they associate with Him.”” [Tawbah 9:31]
Silsilatul-Hudaa wan-Noor, 1/320.