What is the duty of Muslims towards humankind and is the corruption of Muslims equated to the corruption of the world? If so why?

Yes indeed the corruption of Muslims is equated to the corruption of the modern world, and this is not a statement of bias. Rather, it is a clarification of realities concerning the role of man in this world. Muslims believe that Islam is the final and seal of all religions and Prophet Muhammad is the seal of all prophets and messengers from God to humanity, and the people who follow this path and who also acknowledge all of the prophets and messengers before Muhammad are rightfully called the last nation.

Accordingly God has tasked this last nation with calling others to this way as He has commissioned them with correcting the ills of the world and by so doing create a better society for mankind: “Thus We have appointed you a middle nation, that you may be witnesses to mankind, and that the messenger may be a witness to you.” and “You are the best community that has been raised up for mankind, you enjoin right conduct and forbid indecency; and you believe in God.” The community of Islam is therefore a nation of witnessing and a nation that has been ordered to better the world, to enjoin the right and forbid the wrong. Therefore if this nation becomes corrupt, then the world has become corrupt.

The early generation of Muslims understood this concept well as can be seen from the statement of the companion Rab‘iuy ibn ‘Amir who addressed the ruler of Persia, Rostom, by saying “we are a people who have been sent by God to take who wills from the slavehood of other men to the servitude of God, and to take who wills from the narrowness of this world to the expansiveness of this world and the next, and to take who wills from the tyranny of religions to the justice of Islam.”

This great task that God has given Islam and those who follow its teachings guides the actions of Muslims, which is ultimately to save humanity and to take it from darkness into light. In other words the path to success is lighted by the light of Islam and were Muslims, who carry this light, to be corrupted the path will not be lit. Divine aid, however, is always at hand, “they seek to put out the light of God by their mouths but God continues to manifest His light however much the disbelievers hate it.” We ask God for peace and wellbeing for the world and God is Most high and Most knowledgeable.