Gerhard and Walther

Basically, there are five auxiliary means (of receiving and acquiring godliness): 1. The hearing or the reading of God’s Word. 2. The reception of the Eucharist. 3. Sacred Meditations. 4. Diligent prayer and calling upon God. 5. The suppression and taming of the body.—Johann Gerhard, Schola Pietatis II:30. 

[The people] are thus instructed to base their faith, not on man’s testimony, but on the Scriptures, and to fight with the sword of the Spirit. They are also commanded to examine and judge all teachers according to God’s Word, and not let themselves be seduced by false prophets.—C. F. W. Walther, God Grant It!, p. 323.