The core fear of legalism is that grace can lead to sin… That freedom in Christ can become a license to sin. It’s why when a grace-proclaimer blows it, the legalist quickly accuses them of taking grace too far.
And yet, to this very concern Paul responds in Galatians 2, “Certainly not! For if I build again… I make myself a transgressor.” What he’s saying is if I sin while enjoying God’s grace thereby reestablishing those things that were rendered vain… Is it Christ’s fault? No! It’s mine! I’ve made myself a transgressor!”
He then adds… “For I through the law died to the law that I might live to God.” In context Paul’s saying sin in the life of the believer should never be attributed as a failure of grace, but rather a failure to live consistently in grace.
Don’t forget the entire purpose of grace is that it accomplishes a work the Law never could. While the law demanded you “live to God,” it’s grace that enables you to “live to God” as a reciprocation of His favor! It’s why this fear is misguided. You can never take grace far enough and sin is the indicator you haven’t!
Sure the law restricts rebellion, but Jesus’ love transforms the heart of the rebel. Grace works because it replaces your desire to sin with a desire for Godliness, the ambition to please self with a pursuit to please Jesus!
Understand… “I’m saved by grace so I can do whatever I want” is a correct statement… However, if by “whatever I want” you imply something other than pleasing Jesus then at best you don’t understand “Grace” or at worst you aren’t actually saved!