Allah has commanded us to enjoin the good and forbid the evil, and this duty cannot be rendered without power and authority. Likewise, all other social duties such as jihād, maintaining peace and order, justice, organizing ḥajj and ‘īd festivals, redressing abuses, helping the oppressed, enforcing the ḥudūd, and so on, cannot be carried out without political power and authority.
It must be known that this aspect of Islam, i.e. the enjoining of what is right and forbidding of what is wrong, has largely been neglected for a very long time and very few aspects of it remain. Yet it is very important, indeed it is the principle that ensures society remains on the right course. When evil spreads, punishment is inflicted on the good and the bad alike. Unless people stop injustice, Allah may well extend his punishment to all of them. He says: ‘Let those who would go against His bidding beware, lest some affliction or painful suffering befall them’ (24:63). Its benefit is great indeed, particularly because it has been largely neglected, and a person who seeks success in the life to come and hopes to earn Allah’s pleasure should be keen to undertake this duty.
The Caliphate 