Anyone who has ever been to a Catholic wedding will recognize today's second reading, from 1 Corinthians. It is full of some of the most quotable lines of St. Paul's writings.
"If I speak in human and angelic tongues, but do not have love, I am a resounding gong or a clashing cymbal."
"If I have all faith so as to move mountains, but do not have love, I am nothing.""Love is patient, love is kind... It bears all things, believes all things, hopes all things, endures all things.""So faith, hope, love remain, these three; but the greatest of these is love."
If you'll forgive the pun, what St. Paul does here is get to the heart of the matter. Our best actions, our most eloquent words, our noblest deeds, our strongest faith -- all of these things can be spoiled by a lack of love. If I had to summarize in one sentence what God wants from us, I would have to say, "He wants our hearts." He wants us to love.
This helps to explain what Christ meant when He said He did not come to abolish the law, but to fulfill it (Mat 5:17). Think about these things. The Commandments say to not commit adultery. But Jesus says, "everyone who looks at a woman with lust has already committed adultery with her in his heart" (Mat 5:28). Likewise the Commandments say not to kill. But Jesus tells us to not even to be angry with our brothers (Mat 5:22).
The Commandments say "Thou shalt have no gods before me." But Jesus says, "You shall love the Lord, your God, with all your heart, with all your being, with all your strength, and with all your mind..." (Lk 10:27).
You see how Jesus' teachings do not contradict or do away with the Commandments, but rather get to the heart of their meaning. Christ goes on to say in the same passage from Luke that you should "love your neighbor as yourself." It follows if you love your neighbor, you will not desire to lie to him, steal from him, kill him, seduce his wife, or covet his possessions, etc. Just as if you love God with all your heart, you will not take His name in vain, disobey His commands, or worship false gods (by treating other things as if they are more important than God is).
This is why St. Augustine could summarize the whole of the moral law in one sentence. "Love God; then do as you will." He did not mean this in a modern day, relativist sense. Some mistakenly interpret Augustine today to mean we have permission to do whatever we wish, so long as we love God. This is not true. There are some things which we may never do because they are contrary to our nature, contrary to the way God made us. We call these mortal sins. They are beneath our dignity and actually cause us spiritual damage when we do them; things such as murder, adultery, fornication, blasphemy, dishonesty, theft, and the like (things which violate the Ten Commandments). What St. Augustine means is that if we truly love God, we will have no desire to do these things. In fact, the thought of them abhors us. So if you truly have love of God in your heart, you are free to do what you will, because you will only desire to do what is pleasing to God.
So how do we increase our love for God and neighbor? We decide to love. Today.
Think about this: Jesus commands us to love. This means that love is an action, an act of the will, something we can make up our minds to do. It is more than just a human emotion. If love were simply an emotion, Jesus could not have commanded it of us. You cannot command someone to feel an emotion. Telling someone who is sad to "feel happy," is ineffectual. If we could choose to feel happy, no one would ever feel sorrow! You cannot choose to feel frightened, or joyous, or frustrated. These are things that happen to you, not things you can choose.
But love is different. You can choose to love. God would never command us to do something impossible. Love is an act of the will. And it is like anything else we do -- it is a skill we can practice and improve over time. When one first begins to love it can be shaky, haphazard, and require great effort. But over time, with practice, it can become effortless and graceful. The great practitioners of love do so with marvelous achievement! (Think of the saints as our "Lovers Hall of Fame").
One final -- and essential -- fact about love. God is love (1 Jn 4:8). This is the crux of St. Paul's teaching. We can perform mighty deeds and achieve all that is great in the eyes of man. But if we do it all without love, we do it without God.