He said to his students, “To be effective preachers you must be sound theologians” (see note 6). He warned that “those who do away with Christian doctrine are, whether they are aware of it or not, the worst enemies of Christian living… [because] the coals of orthodoxy are necessary to the fire of piety” (Spurgeon_Piper)
“Some excellent brethren seem to think more of the life than of the truth; for when I warn them that the enemy has poisoned the children’s bread, they answer ‘Dear brother, we are sorry to hear it; and, to counteract the evil, we will open the window, and give the children fresh air.’ Yes, open the window, and give them fresh air, by all means… But, at the same time, this ought you to have done, and not to have left the other undone. Arrest the poisoners, and open the windows, too. While men go on preaching false doctrine, you may talk as much as you will about deepening their spiritual life, but you will fail in it” (Spurgeon_Piper)