It is always necessary that the substance or essence of a person be good before there can be any good works and that good works follow and proceed from a person who is already good. Christ says in Matthew 7:18: A good tree cannot bear bad fruit, nor can a bad tree bear good fruit.... The fruit does not make the tree good or bad but the tree itself is what determines the nature of the fruit. In the same way, a person first must be good or bad before doing a good or bad work.

pp. 74-75 - The Freedom of a Christian (1520)