He grew up in a church where the only music accepted for worship was the Psalm in a poetic form; the words, of course, were not bad, after all it was the Word of God being sung, but the melodies were not good, and the young Isaac complained about them. One day, someone said it was the father while others said it was a deacon, a man told him “Well, give us something better, young man.” With God’s inspiration, he started to pen hymns for his own congregation, and many of them were a Psalm with a New Testament language.
“Joy to the World” was not intended to be a Christmas hymn, but a paraphrase of the Psalm 98:7-9. “Let the sea, and all that fills it; the world and those who dwell in it! Let the rivers clap their hands; let the hills sing for joy together before the LORD, for he comes to judge the earth. He will judge the world with righteousness, and the people with equity” (ESV).
Robert Kalis said about this hymn: “The author transformed the old Jewish psalm of praise for some historic deliverance into a Christian song of rejoicing for the salvation of God that began to be manifested when the Babe of Bethlehem came ‘to make his blessing flow far as the curse is found.’ This is one of the most joyous hymns in all Christendom because it makes so real what Christ’s birth means to all mankind.”
The melody is from a passage of Handel’s “Messiah” especially the first measures; they are similar to the introduction of the chorus “Lift Up Your Head” (Psalm 24).
“Joy to the World” might not be a Christmas hymn, but it's lyrics match perfectly with the glorious first advent of our Lord, and it points to the second one.
Joy to the world! The Lord is come!
Let earth receive her King;
Let ev'ry heart prepare Him room, and heav'n and nature sing.
Joy to the earth! The Savior reigns;
Let men their songs employ,
While fields and floods, rocks, hills, and plains repeat the sounding joy.
No more let sins and sorrows grow, nor thorns infest the ground;
He comes to make His blessings flow far as the curse is found.
He rules the world with truth and grace,
And makes the nations prove the glories of His righteousness, and wonders of His love.
In His service.