The readings for this Sunday are about rejoicing.
So what did John the Baptist say? What is there to rejoice about?
It helps in thinking about this question to have some sense of what the bad news is.
The Second Reading follows the call to rejoice with an exhortation to have no anxieties. The bad news is everything that raises those anxieties. The First Reading spells out some of it. There are enemies; there are misfortune—sickness, poverty, unemployment, natural disaster, and all the rest.
It is possible to find some peace about all these things by bringing them to God in prayer and putting your trust in him. At any rate, that is the antidote to these anxieties recommended by this reading.
But a person can have anxieties that are harder to bring to God. There are the relationships you have broken, the wreckage you have made of things at home, the failures you are culpable for at work. Sin can paralyze any effort at joy, in loving relationship with God and others. You can put your trust in God; but what happens when you know that God can put no trust in you? What happens to joy in the face of this thought?
That is the bad news.
But this is also where the good news comes in. The First Reading promises that God will rejoice over you. And why? The answer is also in the First Reading: God will renew you; and when he does, you will be so lovely that God himself will make songs about you and for you, and he himself will sing them to you.
That is amazing good news, isn’t it? But how can it be?
This is where the good news of John the Baptist comes in. Christ will baptize you with the Holy Spirit, and the Holy Spirit will then dwell in you. Christ is Emmanuel, God with us, and he brings God the Holy Spirit into us. When God is with you and in you, how can you keep from singing for joy?