God's law is the definition of love and God's law also tells us much about God and His justice.  God's law is the definition of justice.  Those who argue with this must consider that the all-knowing, all-wise God may just be more intelligent than the creature that God created.  For some egos, that may be a difficult concept to comprehend.

These commands, don't pervert marriage, kill, steal, or lie, don't want what someone else has or be mad that they have it--or any other commandment, is simple to understand: love thy neighbor.

For this, Thou shalt not commit adultery (Any Perversion Of Marriage Including Fornication, Sensuality, and Any Other Such Perversion), Thou shalt not kill, Thou shalt not steal, Thou shalt not bear false witness, Thou shalt not covet; and if there be any other commandment, it is briefly comprehended in this saying, namely, Thou shalt love thy neighbour as thyself.

Consider the following quote from The Feast of Tabernacles by George Warnock:

So it is that the Cross of Christ becomes the beginning of a new era for the children of God. Old things begin to pass away, and all things begin to become new. The bondage of the world, the flesh, and the Devil, gives way to a liberty in the Spirit, and a life of servitude to the God of our salvation. "Being then made free from sin, ye became the servants of righteousness." (Rom. 6:18). From the time we receive Christ as our personal Saviour, and really partake of the benefits of Calvary's Cross--from that very hour we begin a new life in God. And whereas, we once served the enemy of our souls under cruel bondage, now we have become the voluntary bond-slaves of Christ. And after all, the only liberty man will ever find in this world is the liberty which he drives in becoming the "slave" of the Lord Jesus. Paul delighted in calling himself a "doulos," a "bond-slave" of Christ. Man is only free when he is bound to Christ with a chain of love and friendship which neither the cares of life nor the attacks of Satan can sever.