Because He favors His servants, God the Blessed and Supreme gave them intellect, He gave them the power to refine and purify themselves, He sent the prophets and awliya [the friends of God, saints, holy men] to guide people and to help them to reform themselves so that they do not fall into the severe chastisement of hell.
(Extracted from Imam Khomeini's famous works "the comat with the self")