Mrrzy, according to Rise Up Singing, the first two verses of that Hymn for Nations are by Josephine Daskam Bacon, and the third by Don West.

Here's another set of hymn lyrics for the tune; it's closely based on Psalm 98. I learned it from the North American hymnbook of the Reformed Presbyterian Church (who sing psalms exclusively, and a capella as a matter of principle); which means that it might also appear in the old Scottish Presbyterian Psalter.

PSALM 98

Sing a new song to Jehovah
For the wonders he has wrought;
His right hand and arm most holy
Have to him the victory brought.
Lo, Jehovah his salvation
Has to all the world made known;
In the sight of every nation
He his righteousness has shown.

Mindful of his truth and mercy
He to Israel's house has been;
Of our God the great salvation
All the ends of earth have seen.
Sing, o Earth, sing to Jehovah,
Shout aloud, rejoice, and sing,
With the harp sing to Jehovah,
With melodious voice and string.

Sound the trumpet and the cornet,
Shout before the Lord, the king;
Seas and all their fulness, thunder,
Earth and all its people, sing.
Let the rivers in their gladness
Clap their hands in one accord;
Let the mountains sing together
And rejoice before the Lord.

(skipping to the second half of the melody)
For behold, he surely cometh
Judge of all the earth to be;
He with right will judge the nations
And the world with equity.