Whatever, over and above good life-conduct, man fancies that he can do to become well-pleasing to God is mere religious delusion and counterfeit worship of God.
Alles, was ausser dem guten Lebenswandel der Mensch noch thun zu können vermeint, um Gott wohlgefällig zu werden, ist blosser Religionswahn und Afterdienst Gottes.
Original text (German)
Notes from Wikiquote
Book IV, Part 2, Section 2