According to what we have heard, Hazrat Mahdi (as), when he governs, when he spreads the religion and when he revives the Sunnah, the scholar in Medinah [big city] who is used to superstitions will be baffled by the commands of Hazrat Mahdi (as) since he regarded the superstitions to be good and implemented them as a kind of worship and will say "This man has destroyed our religion and killed our nation." Hazrat Mahdi (as) will (intellectually) kill [defeat] this scholar and declare that the superstitions he thought to be good are actually bad.
This is the blessing of Almighty Allah. He gives it to whomever He wills. His bestowal is abundant. (Letters of Rabbani, Volume 1,Page 318)