Is the grace that saves us also a license to sin?
No. Grace saves, and believers live and walk by grace, but that is never a license to sin. Scripture never teaches that being under grace means one may do as one pleases; Paul calls that slander and says condemnation is sure.
Les explains that Paul was slanderously reported as teaching that once a person is saved by grace, he is at liberty to do whatever he wants. Les says Scripture never teaches that, and Paul answers that such condemnation is sure. Les then directs attention to Romans 6, and first Romans 5:20, showing that we are saved by grace, live by grace, and walk by grace, but that is not license. Romans 5:20 also shows that no matter how far down a person can go into sin and wickedness, God's grace is always capable of going even lower and bringing him back up to righteousness.