Read what Martin Luther said about the Spiritual Estate in Luther's Works, volume 46.
“I hope, indeed, that believers, those who want to be called Christians, know very well that the spiritual estate has been established and instituted by God, not with gold or silver but with the precious blood and bitter death of his only Son, our Lord Jesus Christ [1 Pet. 1:18–19]. From his wounds indeed flow the sacraments (they used to depict this on broadsides). He paid dearly that men might everywhere have this office of preaching, baptizing, loosing, binding, giving the sacrament, comforting, warning, and exhorting with God’s word, and whatever else belongs to the pastoral office. For this office not only helps to further and sustain this temporal life and all the worldly estates, but it also gives eternal life and delivers from sin and death, which is its proper and chief work. Indeed, it is only because of the spiritual estate that the world stands and abides at all; if it were not for this estate, the world would long since have gone down to destruction" (LW 46:219–220).