When we think of love being the fulfillment of the law we think of it as in me loving I’m fulfilling the requirements of the law but thats not what its saying.  

Love isn’t the completion of the law in the sense of if I’m loving then I’m doing everything right.  It’s the completion in the sense that the law came to do something to you and what it came to do was to replace the fear in your heart with the love of God. 

The best way I can describe love as the fulfillment of the law is by quoting John when he said perfect love casts out fear.  

The fulfillment of the law would be for the fear that was in your heart to be replaced with love.  It would be for love to be perfected in your heart; for love to have its perfect work in your heart by purging your heart from fear and replacing it with the love of God.  

That’s why John said perfect love casts out fear.  The end goal of the law of God is that it would come and purify your heart from fear and replace it with love.  

It would come and set before your face the wondrous work of God to conquer your sin and death and give you blessing and life as a gift.  This would purify your heart from the fear thats in the world through death and corruption and replace it with love.

The psalmist said the law of the Lord is perfect restoring the soul.  He’s not talking about carnal ordinances we perform there.  He’s not talking about thou shalts and thou shalt nots.  He’s talking about the Word of life that was made flesh in Jesus.  The Word of life is the law of God and it came to restore your soul by replacing the fear in your heart with the love of God.  

That’s the fulfillment of the commandment.  Not you loving to fulfill the commandment by what you do but Jesus immersing you in the love of God.

Now we will love each other but that’s the fruit of the law having been fulfilled in us not the thing that fulfills the law.

The fear of death; the fear that comes from thinking you are separated from some good thing needed for life and godlikeness is the biggest stumbling block to us seeing love manifesting towards one another.  

You cannot find love born in your heart for your neighbor if it is filled with fear.  Jesus could never have loved the world as they were crucifying him if the fear of death was in his heart.  He could never have loved the world if he thought he needed to preserve the life he had from the world.  The pharisees were unable to find love in their heart for Jesus because of the fear that came from thinking they must preserve their own lives.