September 14 marks Holy Cross Day. In honor of the cross of Christ, here are a couple of justly famous paragraphs from Martin Luther’s Heidelberg Disputation (1518) on what it means to be a theologian.
20. He deserves to be called a theologian, however, who comprehends the visible and manifest things of God seen through suffering and the cross. The manifest and visible things of God are placed in opposition to the invisible, namely, his human nature, weakness, foolishness. The Apostle in 1 Cor. 1:25 calls them the weakness and folly of God. Because men misused the knowledge of God through works, God wished again to be recognized in suffering, and to condemn »wisdom concerning invisible things« by means of »wisdom concerning visible things«, so that those who did not honor God as manifested in his works should honor him as he is hidden in his suffering (absconditum in passionibus). As the Apostle says in 1 Cor. 1:21, »For since, in the wisdom of God, the world did not know God through wisdom, it pleased God through the folly of what we preach to save those who believe.« Now it is not sufficient for anyone, and it does him no good to recognize God in his glory and majesty, unless he recognizes him in the humility and shame of the cross. Thus God destroys the wisdom of the wise, as Isa. 45:15 says, »Truly, thou art a God who hidest thyself.« So, also, in John 14:8, where Philip spoke according to the theology of glory: »Show us the Father.« Christ forthwith set aside his flighty thought about seeing God elsewhere and led him to himself, saying, »Philip, he who has seen me has seen the Father« (John 14:9). For this reason true theology and recognition of God are in the crucified Christ, as it is also stated in John 10 (John 14:6) »No one comes to the Father, but by me.« »I am the door« (John 10:9), and so forth.
21. A theology of glory calls evil good and good evil. A theology of the cross calls the thing what it actually is. This is clear: He who does not know Christ does not know God hidden in suffering. Therefore he prefers works to suffering, glory to the cross, strength to weakness, wisdom to folly, and, in general, good to evil. These are the people whom the apostle calls »enemies of the cross of Christ« (Phil. 3:18), for they hate the cross and suffering and love works and the glory of works. Thus they call the good of the cross evil and the evil of a deed good. God can be found only in suffering and the cross, as has already been said. Therefore the friends of the cross say that the cross is good and works are evil, for through the cross works are dethroned and the »old Adam«, who is especially edified by works, is crucified. It is impossible for a person not to be puffed up by his »good works« unless he has first been deflated and destroyed by suffering and evil until he knows that he is worthless and that his works are not his but God’s.