Let us become like Christ since he became like us. He assumed the worse that He might give us the better; He became poor that through His poverty we might become rich; He came down that we might be exalted; He was dishonored that He might glorify us; He died that He might save us; He ascended that he might draw us to Himself, who were lying low in the fall of sin. Let us give all, offer all, to Him who gave himself a ransom and reconciliation for us. (In Defense of His Flight, Gregory of Nazienzen, 371 AD)
St Gregory gets right in the face of much of today’s morality, which focuses on doing what is going merely because it is right. In other words, doing good because it is the law. All too often today, little emphasis is placed on doing good out of devotion to Christ. If all we have is conduct based on law, it is because the benefits obtained for us by Christ remain only in the cognitive and mental part of our reality. We know he is good and speaks the truth so we feel obligated to do what he says. Yet, experiencing Jesus requires that we live in the truth of what Jesus has procured for us to the point that we actually desire to respond by do what is pleasing to our Lord. This is what is meant in the New Testament by love fulfilling the law.
If you really fulfill the royal law according to the Scripture, "You shall love your neighbor as yourself," James 2: 8