"Sin" (from the testamental Greet word "hamartia" which means "missing the mark") is inevitable. God knows how many times I've missed the mark just his morning.
I also believe that when Jesus said "Go and sin no more," he uttered these words in the same spirit with which he repeatedly admonished people NOT TO TELL ANYONE about his miracle-working.
Jesus was not a bean-counting dolt.
He knew full well that NOT ONE PERSON would obey him.
Was he setting them up to be disobedient?
I don't think so.
Peter got it right.
Love Covers A Multitude Of Sins
There is much more irony, paradox and humor in the gospels than your moral rigidity can allow.
But if you want to stay rigid, have at it.
Personally I have no doubt that everything is finally forgiven and that apokatastasis is real.