What fruit? asks Paul. What sort of fruit did you produce “when you were slaves of sin?” (Romans 6: 20) You produced the fruit of death is his answer. “For the wages of sin is death.” (Romans 6: 23) This fruit of sin and death is fruit of which you are now ashamed. And, “just as you offered the parts of yourselves as slaves to moral impurity, and to greater and greater lawlessness, so now offer them as slaves to righteousness, which results in sanctification.” (Romans 6: 19) After all, says Paul, “you have been liberated from sin and have become enslaved to God” so that now “your fruit…results in sanctification — and the end is eternal life.” (Romans 6: 22)
So what fruit are you producing? Jesus says a tree is known by its fruit — a bad tree is incapable of producing good fruit.
I may misunderstand fruit trees, but I believe a good tree is capable of producing fruit which goes bad — fruit on a good tree does occasionally rot and fall to the ground unfit for eating. But as a good tree grows stronger and more rooted in its soil, its fruit is more and more often good for eating.
As Paul exhorts, give your “allegiance to righteousness.” (Romans 6: 20) “Walk in a new way of life. For if we are joined with [Christ] in the likeness of His death, we are certainly also in the likeness of His resurrection.” (Romans 6: 4 – 5) Therefore “consider yourselves dead to sin but alive to God in Christ Jesus.” (Romans 6: 11)