True knowledge of God, therefore, does not come on a theological platter. We are predisposed do distort things, to see wrongly, and to speak falsely. We construct a doctrine of God amenable to our own projects. So the only way to know God is through suffering, the suffering of the one who saves us.
God can be known and had only through suffering the divine deed of the cross. The cross does not merely inform us of something. It attacks and afflicts us. Knowledge of God comes when God happens to us, when God does himself to us. We are crucified with Christ. The sinner, the old being, neither knows nor speaks the truth about God and consequently can only be put to death by the action of God.
In the cross, God has literally taken away from us the possibility of doing anything of religious merit. Religiously, we like to look on ourselves as potential spiritual athletes desperately trying to make God's team, (having, perhaps, just a little problem or two with the training rules). We have a thirst for glory. We feel a certain uneasiness of conscience or even resentment within when the categorical totality of the action of God begins to dawn on us. We are always tempted to return to the safety and assurance of doing something anyway.
But to surrender the "wisdom" of law and works, or better, to have it taken away, is the first indication of what it means to be crucified with Christ.
-- Gerhard O. Forde
On Being a Theologian of the Cross