Everyone claiming to be a Muslim believes in the sovereignty of Allah alone and tries to follow the canons of Islam. Yet there are two things. One is Deen and the other is implementation of Deen. Deen we find in the book of Allah and for the implementation of Deen the best authoritative example we find, is in the life of the Prophet (PBUH) and his companions. In an Islamic country, the State is responsible for the implementation of Deen and it is for the elected legislators to make rules in accordance with the book of Allah and precedents obtaining from the history of law making in Islam.
In the absence of Central Authority of Law making every one has assumed the role of explaining Shariah; very often to suit the requirements of his own cult and clan. This is the cause of diverse views and a source of confusion. Once the responsibility of law making is assumed by a central authority, sects will cease of exist automatically.