There is a piece of me that would prefer the text above to read: The disciples were filled with the joy of the Holy Spirit, since it is the Spirit who is the source of Christian joy. When we are alive in God's spirit, there is always joy, a delight if you like in the realization that God dwells within us, strengthens us and empowers us to live the Gospel plainly and fully.
Joy is very different from happiness. While happiness is almost always fleeting since it is attached to something very particular like a lovely Spring day or one's birthday, joy lasts because it is a gift for the soul, one that cannot be taken away or spent. Joy, like salt in meat, penetrates and becomes part of who we are and how we must live.
The joy of Jesus' disciples astounded their listeners. How could Jesus' friends be so joyful about a hero rabbi who had been beaten and crucified on a garbage heap? How could they sustain a life of joy in the face of so much opposition from the Jewish leaders? The disciples had been transformed by the Spirit and it was the Spirit alone that sustained them in all things, but especially in joy. Their joy was also, no doubt, the cause of their success in proclaiming the Good News.
Today, remember a joyful moment in your life and be grateful.
What keeps you from being joyful in faith?