Continuing with his application in verse 17, John highlights the importance of Christians acting on love rather than merely thinking about it. It is important to communicate love through words, but it is also essential to do so through actions. Jesus not only taught about love but also demonstrated it with powerful actions. "Indeed and in truth," His death on the cross offered the strongest proof of His love. 
The mark of a godly character is one that reflects the likeness of Christ, which is to love others as Christ loved us. Unlike every other form of human love, the love for which the Bible speaks is uniquely imparted to the child of God by the indwelling Spirit of truth and love. In the end, Jesus laid down His life for both His friends and enemies. As He sacrificed His life for us, we are instructed to do the same for others.
The ability to love in deed and in truth is a supernatural power that can only be achieved by a born-again believer who is walking in Spirit and truth. When one has died to self-life and abides in Christ, he or she is able to love in Spirit, in word, in deed, and in truth.

Dear Heavenly Father, thank You that I am Your child and that Christ paid the price for my sins by dying on the cross. The resurrection of Christ has made me a new creation, receiving a new life in Him. It is my prayer that the love of the Lord Jesus will flood and fill my being so that it does not only flow out to others in words and actions but also in spirit and truth. 
In Jesus's name I pray. Amen.