Luther's Gospel

Or, the gospel. Mark Noll, in Turning Points: Decisive Moments in the History of Christianity, p.169-170:

Luther eventually cam to think that his earnest efforts as a monk were rooted in the theology of glory. He believed that systematic, conscientious, ardent, self-denying religious service would win acceptance with God, peace of soul, respect from his fellow spiritual pilgrims, and, in the end, an easful death. But all such notions were banished when he found the cross....

As Luther constantly repeated, the cross must always remain utterly scandalous. It was a scandal for the Jews, and all who sought God through moral exertion; it was a scandal for Greeks, and all who sought God through the exercise of the mind. The cross, for Luther, revealed the judgement of God that no amount of human work could make humanity successful; no amount of diligent study could make humanity truly wise; no amount of human exertion could provide enduring joy. The cross, in sum, was God's everlasting "no" to the most fundamental human idolatry of regarding the self as a God. It was God's final word of condemnation for all efforts to enshrine humanity at the center of existence.

So what, then, is the answer to this conundrum? Noll quotes Luther directly, p. 170:

For where man's strength ends, God's strength begins, provided faith is present and waits on him. And when the opposition comes to an end, it becomes manifest what great strength was hidden under weakness. Even so, Christ was powerless on the cross; and yet there he performed his mightiest work and conquered sin, death, world, hell, devil, and all evil. Thus all the martyrs were string and overcame. Thus, too, all who suffer and are oppressed overcome.

Noll concludes, p. 170:

To embrace the scandalous cross is to be embraced in turn by Jesus. The blood-streaked figure enfolds those who come to him and ushers them into the kingdom of God. The theology of the cross shows us how to become a child of God.