Jesus in these six antithesis is not negating the law, but explicating it. He isn’t countering the law, but the Pharisees’ wooden interpretation of it. The Pharisees read the law like corrupt lawyers, not lovers. They looked for loopholes in the law under the guise of seeking righteousness and justice. They used the law pursue sin disguised as righteousness. They put white dresses on black sins.
As depraved sinners we don’t want to pursue holiness, which is where the law thrusts us, we want to know where the line is. So we ask, “When does sex become sex?”, or “It it gossip if…?” But what you really ask by such questions is, “How close can I get to darkness? How far can I venture from the light while superficially suppressing my conscious so that I feel good about myself?” We want to flee the light while giving the appearance of avoiding darkness. When we ask such questions we are seeking answers that will make us feel better about our rebellion. We use the law to pursue sin, not righteousness.
Sons and daughters of the kingdom then read the law and keep the heart of it, not so that God will be our Father, but because He is our Father (Matthew 5:48). We read the law with delight (Psalm 1:2), seeking reasons, not exceptions. We read it this way not to gain salvation, but because reading it this way is His salvation in our heart. We read it this way not to get into the kingdom, but because the kingdom has gotten into us. Because of His love, we read the law as lovers, not lawyers.