Legalism vs Holiness
Just as in Colossae, those who tend toward legalism are characterized by focusing on works, adding to the law being concerned with external appearances, and imposing those same things on others. It often leads to despair and frustration and is not a result of what Christ has done in us but trying to add to what he’s already done. The other temptation is to minimize the law and obedience to it, which also must be avoided.
We ought to be concerned with holiness, which is always concerned with how God sees us rather than others and is a matter of the heart. It’s about applying the law of God to all of life, where there are no loopholes or corners to be cut. Though it doesn’t preclude a strong confrontation of sin since we are to be concerned with the holiness of God, it’s ready to give others the benefit of the doubt and is quick to forgive repentant hearts as Christ forgave us.