‘Truly, you are a God who hides himself, O God of Israel, the Saviour’ is a verse which has long held a fascination for theologians. Aquinas, Luther, Brunner, and Barth all speak of a deus absconditus. They all, especially Barth, stress that the main characteristic of God is that he reveals himself. His hiddenness is, therefore, only a means to that end. Faith is necessary before anyone can gain knowledge of God. So Ulrich Simon in his commentary on Second Isaiah, a commentary with a markedly Barthian flavour, takes Isaiah 45:15 as the voice of the nations as they experience what he calls ‘Messianic action’. He writes: