Paul ends his letter to the Galatians by returning to the same theme he had hammered from verse 1: the gospel. He writes, “But as for me, I will never boast about anything except the cross of our Lord Jesus Christ” (Galatians 6:14a CSB).

All of us boast in something. As in Galatians, some people boast in how well they keep the law. Some boast in how talented or beautiful they are. Others boast in how much they know. My boast, Paul says, is the gospel.

Some of you may think that the gospel is not that impressive. Perhaps you believe it, but you aren’t sure you could “boast” in it. But according to Paul, the gospel is the wisdom and glory of God and carries with it the power of the new creation. Only a fool would trade it for any kind of technique or knowledge or ritual, no matter how glamorous it may seem. The gospel is stronger than the greatest power in the world.

Martin Luther understood this. A few weeks ago, we celebrated the 500th anniversary of the beginning of the Protestant Reformation. The Reformation began, in large part, when Luther “rediscovered” salvation by faith alone. This doctrine seemed dangerous to the religious leaders of his day, so Luther was called to appear before the authorities. They demanded that he recant.

Cardinal Cajetan, who oversaw the proceedings, threatened to deport Luther to Rome to be imprisoned—and possibly burned at the stake—for heresy. Cajetan pressed Luther further and insisted that he would not be condemned if he would just say one little word: revoco (“I recant”). All Luther had to do was admit that he was wrong, and all of the charges would disappear. Just one word.

But Luther wouldn’t have it. Instead, he wrote,

This much I know, I would be the most accommodating and beloved person if I were to say the simple word revoco …. But I will not become a heretic by denying the understanding through which I have been made a Christian.[1]

As he was returning home, the Roman Emperor Charles V sent out a decree (The Edict of Worms) condemning Luther as a heretic and outlaw and calling for his punishment by death. In the wake of these events, Luther penned the words to the famous hymn, “A Mighty Fortress Is Our God.”

And though this world, with devils filled, should threaten to undo us,
We will not fear, for God has 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.

Cardinal Cajetan urged Luther to say one little word to make everything go away. But Luther held on to another little word: the word of faith.

Luther knew something that we often forget. He knew that in that little word of faith is the power of God. It makes the sinner righteous. It makes the lame walk, the blind see, and the dead live. It frees the captive from the powers of addiction and heals the wounds of years of selfishness and abuse. It is the power of salvation to all who believe it. It turns tragedy into triumph and makes us more than conquerors through him who loves us. When we believe it, it releases in us the power of the Spirit, so much so that not even the gates of hell can withstand us.

When you hide in this fortress, it brings salvation to your kids, healing in your marriage, victory over struggle, and redemption from suffering. Luther’s great hymn—referred to as the “Battle Cry of the Reformation”—closes with these words:

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!

So, when it’s all said and done, what we boast in, what we cling to, is the gospel. In that little word is the mighty fortress of God’s power.