Gerhard and Walther

Here, however, a sensible lamb must learn to properly distinguish the voice of his own Shepherd, Christ, from the howl of the wolves and the voices of heretics, so that it is not misled and steered away from salvation.—Johann Gerhard, Schola Pietatis II:278.

It is not the conviction that natural reason provides that will allow a person to stand before God, but the conviction that God Himself gives by His Holy Spirit.—C. F. W. Walther, God Grant It!, p. 413.