Favored Souls are the result of breeding between a mortal and a celestial being be it an angel or god. As they are touched by the Gods they are gifted with long life and greater power so they may do their God's work in this world.
While many sorcerers have been able to derive their bloodline to some kind of magical creature or event that granted them powers the Favored Soul has the benefit of both arcane and divine magic and has been used by many churches weather it was true or not. Favored souls exist but there has been no proof they are from the God's and their existance would be proof of intervention, something that has been sworn against by all Gods. Many Sages consider the true nature closer to beings favored by the universe or rather lucky individuals that are touched by the universe itself.
The myth is common in one form or another among the more faithful communities and larger cities across the world. Often in remote locations Favored Souls will be considered something along the lines of a Saint or Godsend.
Variations & Mutation
Various faiths and communities have inserted one God over another and few even have said a Favored Soul is the first step in sainthood.
Many plays and fictional accounts portray the hero figure as a Favored Soul, often this will be revealed at the darkest moment as the hero lays dying only for the Gods to bless them and reveal their true nature.