You are my friends if you do what I command you. (JOHN 15: 14)
Under the reign of grace, is the moral will of God (considered as a whole) a request or a command? The word request connotes desire; whereas the word command connotes authority to require. Response to a desire is optional; response to a command is not. So when Jesus said we love Him by obeying His commands, was He using the word command as we ordinarily understand it, or was He using it as an expression of God’s desire? In the realm of grace, does the moral will of God express the desire of God as to how He would like us to live, or does it express the requirement of God as to how we are to live?
Some people readily say God desires that we be holy, but God does not require that we be holy. They maintain that under grace we have been freed, not only from the curse and condemnation resulting from breaking the law but also from the requirements of the law as a rule of life. They believe that to insist on obedience as a requirement for a Christian is to teach legalism instead of grace. In other words, to assign the concept of requirement to the will of God is legalism, but to assign the concept of desire to it is grace.
I believe such a view is a misunderstanding of grace. God’s grace does not change the fundamental character of God’s moral Law. Rather, the grace of God provides for the forgiveness and acceptance of those who have broken the law. The good news of the gospel is that God has removed the guilt we incur by breaking His Law and has bestowed on us the righteousness of Christ, who perfectly kept His Law. Legalism does not consist in yielding obedience to the law. Rather, it is to seek justification and good standing with God through the merit of works done in obedience to the law — instead of by faith in Christ.
~Jerry Bridges, Transforming Grace