The course of the world does not require to be changed by the activity of any person.
What is necessary is to change our outlook to this very world.
This was done for the contemporary generation by the mercy of Sri Caitanya.
It could be only known to recipients of His mercy.
The scriptures declare that it is only necessary to listen with an open mind to the name of Krsna from the lips of a bona fide devotee.
As soon as Krsna enters the listening ear, He clears up the vision of the listener so that he no longer has any ambition of ever acting the part of a reformer of any other person, because he finds that nobody is left without the very highest guidance.
It is therefore his own reform, by the grace of God, whose supreme necessity and nature he is increasingly able to realize, by the eternally continuing mercy of the Supreme Lord.