The religious leaders had gone home frustrated that they couldn’t silence Jesus or have Him arrested. They were going to have to deal with Him publically on account of His notoriety. Their plots had been foiled but they weren’t about to stop. After Jesus comes back to the temple to teach, we see their scheme. They were going to try and outwit Jesus intellectually by making use of their supposed mastery of the Law of Moses.
Jesus takes a stand against the accusers of a woman caught in adultery. Unfortunately, careless Christians and undiscerning unbelievers take this passage to mean that Jesus is showing us that we should never judge anyone, anytime, for any reason. But He is not abrogating the law, or negating it. He knew they were trying to set Him up, but He sets them up instead.
Jesus implies that the accusers were at fault, and had no right (Deuteronomy 17:7). They thought of bringing a charge against Jesus for not honoring the law, when it was they who failed to meet the conditions of the law in this case. The man involved in the adultery was also to be included in the punishment (Deuteronomy 22:22-24).
Jesus was not glossing over her sin, and He was not implying that we must be perfect or we cannot address other people in their sin. He was also not telling her that she must now become perfect. He was saying that she must stop this sort of sin. The days of her accusers were past, and the days of her adultery were over. His forgiving the woman was not conditioned on her repentance, but He clearly sees her repentance as the natural outcome of it.
When our sins have come to light, and yet we find forgiveness, why would we continue to walk down the dark alley (1 John 1:6-10)? When you slide down to live on the back streets of persistent sin, they will not only accuse you, they will accuse Jesus.