Just because we are saved by grace we aren't free to sin. Romans 6:15-23 tells us once we are no longer slaves to sin we should be slaves to righteousness. If we present ourselves obedient to either sin or righteousness, we will gain the outcome of death from sin or life from righteousness. Thanks to the grace of God we have been set free as slaves to sin and are now slaves to righteousness. We must now present ourselves as slaves to righteousness, which leads to sanctification. Because we are now free from sin, where we once were free from righteousness and life, we must now live in righteousness.
"For the wages of sin is death, but the free gift of God is eternal life in Christ Jesus our Lord." verse 23.
Praise God for the Free Gift of Life through Christ.