Why were the Bab and Baha'u'llah sent to the world?
Here is why:
"The purpose of the one true God in manifesting Himself is to summon all mankind to truthfulness and sincerity, to piety and trustworthiness, to resignation and submissiveness to the Will of God, to forbearance and kindliness, to uprightness and wisdom. His object is to array every man with the mantle of a saintly character, and to adorn him with the ornament of holy and goodly deeds." (Baha'u'llah, Gleanings, p. 298)