Many teachers avoid legalism in justification, only to endorse it (unintentionally?) in sanctification.
That is, they present the Christian life as a series of commands for you to fulfill. Living the Christian life becomes an attempt to fulfill the same “to do” list that was completely inadequate to save you in the first place. These teachers forget that the law does not have the power to produce life in you. Period. Whether it is justification or sanctification, the law is a ministry of death and condemnation (Rom 5:20; 2 Cor 3:7, 9), so don’t expect any other result if those laws become the focus of your spiritual life.
And yet…the NT is filled with imperatives. What do you do with them?
Tullian Tchividjian has a suggestion:
Freed from the burden and bondage of attempting to use the law to establish our righteousness before God, Christians are free to look to the “imperatives” of Scripture, not as conditions, but as descriptions and directions as they seek to serve their neighbor. Once a person is liberated from the commonsense delusion that keeping the rules makes us right with God and, in faith, believes the counterintuitive reality that being made righteous by God’s forgiving and resurrecting word precedes and produces loving action (defined as serving our neighbor), then the justified person is unlocked to love, which is the fulfillment of the love (It is Finished, February 7).
In this scenario, NT laws and commands are not the focus, motivation, or goal of your spiritual life. Instead, you, the believer, are already assured of your justification before God through faith in Christ. Therefore, since you’re freed up from doing works-salvation things, you can simply spend your time loving your neighbors in the many ways they need to be helped. Where do the NT imperatives fit with that? If you’re ever in doubt about how best to love your neighbor, the commands are there to describe what love looks like.
Here’s a comparison: you use the commands in your Christian life similar to how you use your rearview mirror while driving. If all you did was look into the rearview instead of focusing on the road, you’d crash, right? Your focus needs to be on the road, not the rearview. Likewise, in living the Christian life, your focus needs to be on Christ, His glory, and what He did for you in the gospel. Those truths are what renew your mind and produce loving action towards you neighbor.
However, sometimes you need to glance into the rearview of the law to avoid crashing into things—but only for a moment. And then you quickly go back to focusing on the road—and the neighbors driving around you.