" The call is not to be taken lightly. For a person to possess knowledge is not enough. He must be sure that he is properly called. Those who operate without a proper call seek no good purpose. God does not bless their labors. They may be good preachers, but they do no edify. Many of the fanatics of our day pronounce words of faith, but they bear no good fruit, because their purpose is to turn men to their perverse opinions. On the other hand, those who have a divine call must suffer a good deal of opposition in order that they may become fortified against the running attacks of the devil and the world. "

― Martin Luther , Commentary on Galatians