Martin Luther wrote "A Mighty Fortress is our God" around 1529. It is based  on Psalm 46--"God is our refuge and strength in the time of trouble."  The video on the left is an instrumental that presents it in gentle praise.

Martin Luther wrote it in German, and I read that there are as many as 80 English translations of it.  

The words are:

Verse 1

A mighty fortress is our God, A bulwark never failing.

Our helper He amid the flood Of mortal ills prevailing.

For still our ancient foe Doth seek to work us woe--

His craft and power are great, and armed with cruel hate,

On earth is not His equal.

Verse 2

Did we in our own strength confide, Our striving would be losing.

Were not the right man on our side, The man of God's own choosing.

Dost ask who that may be?  Christ Jesus, it is He--

Lord Sabaoth His name, From age to age the same,

And He must win the battle.

Verse 3

And though this world with devils filled, Should threaten to undo us,

We will not fear, for God hath willed, His truth to triumph through us.

The prince of darkness grim, We tremble not for him--

His rage we can endure, For lo, his doom is sure:

One little word shall fell him.

Verse 4

That word above all earthly powers, No thanks to them, abideth.

The Spirit and the gifts are ours Through Him who with us sideth.

Let goods and kindred go, This mortal life also--

The body they may kill; God's truth abideth still:

His kingdom is forever.

The second video is of Steve Green singing it.  He sings it powerfully.