The presence of that which goes against Islam is not permitted in the State
The Islamic Aqeeda being a basis of the State obliges that the Islamic State should not have any thought, concept, rule or criterion which has not emanated from the Islamic Aqeeda i.e. not taken from the Book of Allah and the Sunnah of His Messenger (saw). Because it is not enough that the basis of the State be the Islamic creed only in name. Rather this basis should be represented in everything related to its existence, and in every one of its issues whether tiny or great. Therefore, it is not permitted that there should be any concept taken from democracy or nationalism because it contradicts with the rules of Islam.
(from the culture of Hizb ut-Tahrir)