Martin Luther spent his entire pastoral career mining the depths of the cross and applying it to his people. He loved to think about, sing about, write about, and preach about the cross. His whole theological program was cross-centered. Listen to a few of these quotes from Luther.
“He deserves to be called a theologian, however, who comprehends the visible and manifest things of God seen through suffering and the cross.”
“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…for this reason true theology and recognition of God are in the crucified Christ” (emphasis mine).
“God can be found only in suffering and the cross”(emphasis mine).
“Christ must be apprehended as man, before he is apprehended as God; and the cross of his humanity must be sought after and known, before we know the glory of his divinity.”
“The cross alone is our theology.”
These statements capture the heart of Luther’s theology. The cross alone is the starting point and shape of all theology. Alister McGrath sums up this emphasis in Luther’s thinking.
“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 for 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 a proper understanding of the nature of God. The Christian can only speak about the glory, the wisdom, the righteousness and the strength God as they are revealed in the crucified Christ…for Luther, the sole authentic locus of man’s knowledge of God is the cross of Christ, in which God is to be found revealed, and yet paradoxically hidden in that revelation” (emphasis mine).
 Martin Luther, The Basic Theological Writings (2nd Edition), ed. Timothy F. Lull (Minneapolis: Fortress Press, 2005), 49.
 Ibid, 57.
 Ibid, 58.
 Alberto L. Garcia, The Theology of the Cross for the 21st Century (Saint Louis: Concordia Publishing House, 2002), 15.