Let the Christian remain in the world, not because of the good gifts of creation, nor because of his responsibility for the course of the world, but for the sake of the Body of the incarnate Christ and for the sake of the Church. Let him remain in the world to engage in frontal assault on it, and let him live the life of his secular calling in order to show himself as a stranger in this world all the more. But that is only possible if we are visible members of the Church. The antithesis between the world and the Church must be borne out in the world. That was the purpose of the incarnation. That is why Christ died among his enemies. That is the reason and the only reason why the slave must remain a slave and the Christian remain subject to the powers that be.
This is exactly the conclusion Luther reached with regard to the Christian’s secular calling during those critical years when he was turning his back on the cloister. It was not so much the lofty standards of monasticism that he repudiated, as their interpretation in terms of individual achievement. It was not otherworldliness as such that he attacked, but the perversion of otherworldliness into a subtle kind of “spiritual” worldliness. To Luther’s mind that was a most insidious perversion of the gospel. The otherworldliness of the Christian life ought, Luther concluded, to be manifested in the very midst of the world, in the Christian community and in its daily life. Hence the Christian’s task is to live out that life in terms of his secular calling. That is the way to die unto the world. The value of the secular calling for the Christian is that it provides an opportunity of living the Christian life with the support of God’s grace, and of engaging more vigorously in the assault on the world and everything that it stands for.
-Dietrich Bonhoeffer, “The Visible Community”, The Cost of Discipleship