When we are faced with God's great mercy, how should we respond? First, Paul instructs us to love with sincere and genuine affection. Second, we must learn to hate evil, particularly sin that harms innocent people. Third, we must learn to see the world from God's perspective to invest our energy and time in securing and maintaining what is truly good.
The only love that is truly sincere comes from the heart of our Savior. In a Christian life, love is the foremost fruit of the Spirit. This fruit can only be imparted to us by the Holy Spirit Himself as we die to ourselves, abide in Christ, and become like Him. It is common for human love to be flawed and to display self-centered tendencies or to be disguised by hypocritical pretenses. As opposed to this, the love of God is sincere, unaffected, and never fails. 
In this exhaustive defense of the Christian faith, Paul emphasizes the importance of showing godly love. In this way, we demonstrate deep reverence for the Lord as well as tender affection for those within the household of faith according to our gifts and callings. The life of such a person will be one of fruit and an overflowing heart of God's love, one that is beyond comprehension.

Dear Heavenly Father, thank You for Paul's amazing letter to the Romans, which outlines so clearly how we should behave as blood-bought children of God. I want to live my life to Your praise and glory. Through me, may God's love flow to others in all its fullness. In my prayer, I ask that I may cling to what is good and hate all that is evil. By abiding in Christ, I will be free from hypocrisy in my love. 
In Jesus's name I pray. Amen.