This has some special relevance for me these days, and I’ll be posting on this occasionally, Lord willing.
The years 1517 and 1519 are generally regarded as being of decisive importance in the career of Martin Luther, and the history of the Reformation as a whole. The first witnessed Luther’s posting of the Theses on Indulgences at Wittenberg, and the second the historic Leipzig disputation with Johannes Eck. It is all too easy for the historian to pass over the intervening year, 1518, as being little more than the necessary interval between these two pivotal events, a valley nestling between two mountains.
In April of that year, however, at the invitation of Johannes von Staupitz, Luther presided over the traditional public disputation at the assembly of the Augustinian Congregation at Heidelberg. In the course of that disputation, a new phrase was added to the vocabulary of Christendom – the ‘theology of the cross’. In the theologia crucis, we find Luther’s developing theological insights crystallized into one of the most radical understandings of the nature of Christian theology which the church has ever known.
Crux probat omnia. For Luther, Christian thinking about God comes to an abrupt halt at the foot of the cross. The Christian is forced, by the very existence of the crucified Christ, to make a momentous decision. Either he will seek God elsewhere, or he will make the cross itself the foundation and criterion of his thought about God. The ‘crucified God’ – to use Luther’s daring phrase – is not merely the foundation of the Christian faith, but is also the key to understanding the nature of God.
From Alister E. McGrath, “Luther’s Theology of the Cross,” Oxford, UK: and Malden, MA: Blackwell Publishers, ©1985, 1990, pg 1.