Church tradition tells a story of the Apostle John who, when advanced in age, had to be carried to the various gathering of the church in Ephesus. He was the last remaining Apostle, the beloved Elder, and the patriarch of the church in waning years of the 1st century AD. Leadership of the church had been passed to younger and more able men. As is the case with all men at some point in the aging process, John was no longer able to preach and teach and lead in his former manner. Strength and metal capacity simply did not allow for it. But out of respect for both his unique position and enduring faithfulness, at the end of each gathering, the aged Apostle would be asked if he had anything to say. To this request, John is reported to reply, "Love one another."
Week after week, gathering after gathering, John's reply was always the same: love one another. As the story goes, one week one of the leaders of the church replied, "We know that. Do you have any other word for us?" It seemed the Apostle's message was growing stale. To this retort, the Apostle replied, "When you figure that out, I will give you something else." Point made.
John is known as the Apostle of love. He had learned at the feet of Jesus. He had heard Jesus summarize the content of the Law as love God with everything in you and love your neighbor as yourself (Mt. 22:37-40). He had heard Jesus say, "Greater love has no man than this, that one lay down his life for his friends" (Jn. 15:13). The next day he stood at the foot of the cross watching his Savior lay down his life to accomplish his salvation. He had also heard Jesus say, "By this all men will know that you are my disciples, if you have love for one another" (Jn. 13:35). This command to love falls frequently from the lips of Jesus on the night before his crucifixion (Jn. 13:34-35; 15:12-17), culminating in his prayer for their unity (Jn. 17:19-23), for unity has at its basis the uniting love flowing from salvation.
John had also learned that night that loving God results in obedience to God's word (Jn. 14:23-24; 15:9-11, 14). John came to realize that there was an inseparable link between loving God and loving God's people. This truth never left him, for when he desired to write a letter about eternal security, which we know as John's 1st Epistle, he gave three markers: 1) a love for God that resulted in 2) a desire to obey God expressed in 3) love for the people of God. That is the content of the whole book, which is summarized beautifully in the following passage from 1 John 4: 7 Beloved, let us love one another, for love is from God; and everyone who loves is dborn of God and knows God. 8 The one who does not love does not know God, for God is love. 9 By this the love of God was manifested in us, that God has sent His only begotten Son into the world so that we might live through Him. 10 In this is love, not that we loved God, but that He loved us and sent His Son to be the propitiation for our sins. 11 Beloved, if God so loved us, we also ought to love one another. 12 No one has seen God at any time; if we love one another, God abides in us, and His love is perfected in us. 13 By this we know that we abide in Him and He in us, because He has given us of His Spirit. 14 We have seen and testify that the Father has sent the Son to be the Savior of the world. 15 Whoever confesses that Jesus is the Son of God, God abides in him, and he in God. 16 We have come to know and have believed the love which God has for us. God is love, and the one who abides in love abides in God, and God abides in him. 17 By this, love is perfected with us, so that we may have confidence in the day of judgment; because as He is, so also are we in this world. 18 There is no fear in love; but perfect love casts out fear, because fear involves punishment, and the one who fears is not perfected in love. 19 We love, because He first loved us. 20 If someone says, "I love God," and hates his brother, he is a liar; for the one who does not love his brother whom he has seen, cannot love God whom he has not seen. 21 And this commandment we have from Him, that the one who loves God should love his brother also.
Loving like Christ loved, loving in a way that causes you to give up your desires, agendas, or personal advancement for the growth, support, or advance of someone else is fundamentally opposed by our flesh. It does not come naturally and will never be initiated by our emotions. It only comes by gaining the mind of Christ. But when we operate with the mind of Christ for the goals of Christ, acts of love and self-sacrifice upon the altar of others' faith becomes our greatest joy and highest goal, for in loving our fellow believer, we are showing Christ to a watching world and, most importantly, glorifying our Father who is in heaven. True love, as defined by Scripture, is never something we grow past. It is, in many ways, the summation of our theology in action, for we can gauge our love for God by the barometer of our love for our fellow Christians.
 New American Standard Bible: 1995 update. (1995). (1 Jn 4:7-21). La Habra, CA: The Lockman Foundation.