What: Luther said that he had tried again and again, but could not write good treatise on justification. And then it came to him: what better way to express the peace and joy of being declared right with God (Romans 5) than to sing? The more well-known translation is by Richard Massie, "Dear Christians, One and All, Rejoice," LSB 556.
Who: This is another translation by the Reformation era Scotsmen, the Wedderburns.
Changes: I have heavily edited this translation.
Note: "Esay" is the old English version of Isaiah (much like Jeremy is from Jeremiah). Also, the meter is slightly different, so you have to put a syllable for every note of the tune (you'll see what I mean, don't worry).
Tune: The meter is technically 88 88 888, but it can still be sung to NUN FREUT EUCH, LSB 556.
Be blithe, all Christian men, and sing;
Dance and make mirth with all your might.
Christ has brought us great comforting;
Wherefore we may rejoice of right.
A work to wonder what is wrought:
Christ with His blood has us dear bought
And for our sake was made to die.
For with the Fiend and doleful death,
With hell and sin I was forlorn,
The son of ire_ at God's feet;
Conceived, I was, in sin, and born;
I grew up more and more therein
And daily added sin to sin,
Despair was e'er before me.
Where I could not the Law fulfill,
My doings made me no supply;
So blind and weak was my "free" will,
That it did hate all verity.
My conscience cast me into care,
The devil drove me to despair,
And hell was e'er before my eye.
God had great pity on my woe,
Above all measure showed me grace,
When I was yet His cruel foe,
Yet He would cure my careful case;
His love to me He did convert,
From the most deepest of His heart,
Which cost Him dear, to make my peace.
To His beloved Son He said,
"The time of mercy now draws near,
To save man and the fiend invade.
Therefore My heart's own Son so dear:
Go fetch them from the devil's feed,
Tho man o'erthrow sin, hell, and death,
And man restore to health and fear."
The Son His Father did obey,
And came down to the earth to me;
Born of a maid, as writes Esay,
My kind, sweet brother for to be.
He took on Him my nature vile,
And did His might for to exile,
Satan and all his subtlety.
He said, "Thou shalt have victory,
If thou alone on Me depend.
For I will give Myself for thee,
Thy careful quarrel to defend.
For I am thine and Mine thou art,
And of my fame thou shalt have part,
And reign with Me without end.
"Though man shed out My blessed blood,
And also reave My life from Me,
I bear this only for thy good:
Believe that firm and steadfastly.
For my death shall thy death devour,
That sin shall thee condemn no more:
This way, man, shalt thou savéd be.
Thus from this present life I fare,
To My Father celestial,
Thy Mediator to be there,
And send thee My Spirit I shall,
To give thee great consolation,
For all thy sore tribulation,
The truth He shall teach to you all.
My doing, teaching, more and less,
That teach and do unfeignédly,
For this doth God's dear church increase,
And His great name doth magnify.
Beware of men and their command,
Which Me and My Word do gainstand,
My testament I leave to thee.
Nun freut euch, Christen
Martin Luther
Tr. Wedderburn, ed. MDS