1) Our Lady instructed St. Juan Diego to take her requests to the Bishop.
2) The Bishop didn't believe the apparition was authentic.
3) Obedient to the Bishop, the Blessed Virgin, rather than excoriating the Bishop's lack of credulity, sent him a sign ... a "Great Sign" in fact.
4) The Bishop came to believe and millions were converted to the True Faith.
5) A "permanent sign" remains to testify to the events. The inexplicable preservation of the tilma itself is considered miraculous.
For more information on the miraculous image not made by hands, Our Lady of Guadalupe, go here.
Happy feast day to all!