“But the angel said to them, “Do not be afraid; for behold, I bring you good news of great joy which will be for all the people.”(Luke 2:10 LSB)
Isaac Watts penned the famous hymn, "Joy to the World" in 1719. Watt wrote the hymn with Psalm 98 in mind. Interestingly enough, "Joy to the World" was not originally considered a Christmas song as Psalm 98 speaks of the second coming of Christ.
As Christians, the good news of Jesus, is what calls us to sing a new song like Psalm 98:1 says, "Sing to Yahweh a new song." We praise the Lord for what He has done. We praise Him for the incarnation, where God took on flesh to bring salvation to humanity.
Psalm 98:4-6 calls for the entire earth to rejoice in the coming of the King. This is where Watt got the inspiration to write the lyrics "Joy to the world! The Lord is come; Let earth receive her king" We sing these words with great anticipation as we await the fulfillment of the promise that Christ will return. Then, the fullness of His glory will be revealed to all humanity.
We cannot look forward to the second coming of Christ if there was no first coming. We sing "Joy to the World" at Christmas because we look forward to a day when there is truly peace on Earth. Advent is not only looking back at the incarnation, but also looking forward to Christ's second coming. The ultimate joy is still to come, and that is good news!
Keep on!