On what basis is a good deed good? We might say that whatever has the effect of benefiting our neighbor is a good deed. But what if that deed was done out of selfish motive? Generally we do not call such deeds good, but rather self-aggrandizing.
What about the deed done out of guilt? If we act out of a sense of self flagellation, or a desire to atone for our wrong, then have we not put ourselves in the place of the only One who has the power to atone? Indeed, guilt itself was atoned for on the cross. Guilt offerings and sin offerings were done away with because Christ himself is the guilt offering.
Why then do we still find ourselves acting out of guilt? We act out of guilt when our condition becomes the motivation for our actions. We are guilty of all sorts of wrong, so when our condition becomes motivation, good cannot but be done out of guilt. But that is what we are freed from by the cross of Jesus. He died in order that we might now live in relation to him, and not according to our human condition.
Therefore, when we do good for someone out of guilt, we are idolaters. We are turning from a life that is lived according to Jesus and his relationship with us, and turning to a life that is lived according to our human condition.
Now the human condition is such that if we are thorough in the examination of our motives we might likely find that nearly all that we do has a self-referential motive. This might by some short-sighted line of thinking cause us to hesitate to do the good that we might if it is so motivated by guilt. But is not that consideration itself one that is self-absorbed? To the one who hesitates to do good because he is afraid of doing it for the wrong motive, Luther writes “sin boldly”. Because fear is also something from which we are set free.
If we are to answer the first question “On what basis is a good deed good?” then we must answer that a good deed is good when it is a forgiven deed, and so does the will of God.
Sin is a fact and it taints our motives; fear of that sin is yet another sin! What is the solution for such a comical self-defeat? We know that sin is forgiven, so its fact cannot produce fear any longer. While some may do good because of guilt for past wrongs, Christians do good because they are forgiven of all wrongs. Any other reason is idolatry.