Religious Obligations of an Islamic State

[These believers are those who], if We grant them authority in this land, will establish regular prayers and pay Zakah and enjoin what is virtuous and forbid what is evil. (22:41)

This verse of Surah Hajj states that the religious obligations imposed on an Islamic state are establishing the system of Salah, disbursing Zakah, enjoining Ma'ruf and forbidding Munkar.  An explanation of these obligations follows:

In accordance with the Sunnah of the Prophet (sws) that relates to the establishing of Salah at the state level:  
    1. The Muslim citizens shall be bound to say their prayers in the mosques.  
    2. Mosques shall remain under the supervision of the government; this includes the appointment of imams.  
    3. The address of the Friday prayer shall be delivered by the head of state and he shall lead this prayer in the central congregational (Jami') mosque of the capital. The provincial governors shall be entrusted with this job in the provinces while government representatives shall discharge this duty in the various administrative units.

Similarly, in accordance with the Sunnah of the Prophet (sws) regarding Zakah:  
    1. A Muslim citizen who is liable to Zakah shall pay the stipulated amount from his wealth, produce and livestock to the government.  
    2. The government in return, besides spending under other heads, shall try to fulfill the needs of its needy citizens through this money by reaching out to them before they come to it for their needs.  

For the enjoining of Ma'ruf (the good) and for the forbidding of Munkar (evil), the Qur'anic directive is that the state should constitute a group of people which should be entrusted with the responsibility of calling people towards good and forbidding them from evil. In modern terms, this means that a proper department vested with legal authority should be set up by the state for this purpose. This department should function efficiently and diligently to discharge the responsibility entrusted to it. In the words of the Qur'an:  

From within you should a group be constituted such that it should call towards what is virtuous, enjoin good and forbid evil. And only those who make arrangements for this will attain salvation. (3:104)