Carl Trueman on “the most glorious contribution of Martin Luther to theological discourse,” first revealed in Heidelberg during a meeting in 1518:
At the heart of this new theology was the notion that God reveals himself under his opposite; or, to express this another way, God achieves his intended purposes by doing the exact opposite of that which humans might expect. The supreme example of this is the cross itself: God triumphs over sin and evil by allowing sin and evil to triumph (apparently) over him. His real strength is demonstrated through apparent weakness. This was the way a theologian of the cross thought about God.
The opposite to this was the theologian of glory. In simple terms, the theologian of glory assumed that there was basic continuity between the way the world is and the way God is: if strength is demonstrated through raw power on earth, then God’s strength must be the same, only extended to infinity. To such a theologian, the cross is simply foolishness, a piece of nonsense.
Trueman goes on to ask where the theologians of the cross are to be found today:
At this Reformation season, we should not reduce the insights of Luther simply to justification by grace through faith. In fact, this insight is itself inseparable from the notion of that of the theologians of the cross. Sad to say, it is often hard to discern where these theologians of the cross are to be found. Yes, many talk about the cross, but the cultural norms of many churches seem no different to the cultural norms of—well, the culture. They often indicate an attitude to power and influence that sees these things as directly related to size, market share, consumerist packaging, aesthetics, youth culture, media appearances, swagger and the all-round noise and pyrotechnics we associate with modern cinema rather than New Testament Christianity. These are surely more akin to what Luther would have regarded as symptomatic of the presence and influence of theologians of glory rather than the cross. An abstract theology of the cross can quite easily be packaged and marketed by a theologian of glory. And this is not to point the finger at `them’: in fact, if we are honest, most if not all of us feel the attraction of being theologians of glory. Not surprising, given that being a theologian of glory is the default position for fallen human nature.
The way to move from being a theologian of glory to a theologian of the cross is not an easy one, not simply a question of mastering techniques, reading books or learning a new vocabulary. It is repentance.
In another essay, Trueman writes:
This argument is explosive, giving a whole new understanding of Christian authority. Elders, for example, are not to be those renowned for throwing their weight around, for badgering others, and for using their position or wealth or credentials to enforce their own opinions. No, the truly Christian elder is the one who devotes his whole life to the painful, inconvenient, and humiliating service of others, for in so doing he demonstrates Christlike authority, the kind of authority that Christ himself demonstrated throughout his incarnate life and supremely on the cross at Calvary.
See also Gerhard Forde’s On Being a Theologian of the Cross: Reflections on Luther’s Heidelberg Disputation, 1518 and Alister McGrath’s Luther’s Theology of the Cross: Martin Luther’s Theological Breakthrough.