Joy to the world! the Lord is come!
Let earth receive her King;
Let every 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.

The Psalms and Hymns of Isaac Watts, 1806

Scripture References:
st. 1-3 = Ps. 98
st. 2 = Ps. 96:11-12
st. 3 = Gen. 3:17-18

Isaac Watts (PHH 155) wrote this text as a paraphrase of Psalm 98. He published it in his Psalms of David Imitated (1719) under the heading “The Messiah's Coming and Kingdom.” The paraphrase is Watts' Christological interpretation.

Consequently, he does not emphasize with equal weight the various themes of Psalm 98. In stanzas 1 and 2 Watts writes of heaven and earth rejoicing at the coming of the king. An interlude that depends more on Watts' interpretation than the psalm text, stanza 3 speaks of Christ's blessings extending victoriously over the realm of sin. The cheerful repetition of the non-psalm phrase "far as the curse is found" has caused this stanza to be omitted from some hymnals. But the line makes joyful sense when understood from the New Testament eyes through which Watts interprets the psalm. Stanza 4 celebrates Christ's rule over the nations.

Liturgical Use
Christmas Day, but also at any other time of year in relation to Psalm 98. Raised eyebrows at singing "Joy to the World!" in July will lower as soon as the relationship to Psalm 98 becomes clear.

--Psalter Hymnal Handbook