Priesthood and priestcraft are two opposites, wrote Elder Bruce R. McConkie. “One is of God, the other of the devil. When ministers claim but do not possess the priesthood; when they set themselves up as lights to their congregations, but do not preach the pure and full gospel; when their interest is in gaining personal popularity and financial gain, rather than in caring for the poor and ministering to the wants and needs of their fellow men-they are engaged, in a greater or lesser degree, in the practice of priestcrafts.” (Mormon Doctrine, p. 593.)
That is to say, those who practice priestcraft are motivated by mammon, having “corrupt minds” (see D&C 33:4). “Such a man or woman might serve in Church positions or in private acts of mercy in an effort to achieve prominence or cultivate contacts that would increase income or aid in acquiring wealth. Others might serve in order to obtain worldly horrors.” (Dallin H. Oaks, CR, October 1984, p. 14.)