HAPPINESS VS. JOY
There is a pretty common belief that differentiates between happiness and joy. This is one that I believe. Happiness is based on circumstances. Expensive gifts and good food and parties and celebrations and Christmas lights can bring happiness. But they are only temporary. They aren't always there. There are many people who have those things take away. Some have never had them.
Joy comes from within. It transcends what happens to us. Good things that God blesses us with makes the joy swell in our hearts. Like the ocean. Ever been on the ocean or even Lake Erie when there are swells from a storm? Large sections of the water rise up and burst of the side of the boat. I was one on a boat on Lake Erie when there were fifteen foot swells. It was amazing. The boat was large enough that we weren't worried, but you get the sense of power.
Joy has the same capacity if not more so. It swells when God pours out His blessings on you. It overflows onto others. It spills out of your heart in showers of praise and gratitude. Yet, while happiness is often fleeting and disappears when circumstances change (like when Christmas is taken from us). Joy remains constant even in the darkest times. It may not burst from you, but it remains the same. The joy is there while happiness has run away.
This is the joy of Jesus. This is what Christ brings to us when he comes. It is the joy of forgiveness. It is the joy of grace. It is the joy of love. It is the joy of mercy.