Grace doesn't mean that we are sloppy with sin. We have died to sin when we surrendered our lives to the Lordship of Christ. We don't want sin, or its power, to have control over us. We don't want to take lightly the awful cost Jesus paid to cover our sin. The apostle Paul uses the strongest language possible ("By no means!" is way too tame a translation: "God forbid!" "Unthinkable!" "Abomination!" would all be much more accurate.) As those saved by grace, we realize that sin is more than breaking a divine command. Sin is making light of Jesus' love for us by choosing our sin over his sacrifice. Sin is rebelling against the Father who paid such a high price to adopt us into his family. Sin is breaking our Father's heart because we are choosing our sin over our love for him. Finally, sin is choosing our own will rather than God; a choice that leads us down a path of self-destruction.