‘Who could have believed what we have heard?
And who could have seen in this the arm of Yahweh?'
The blank astonishment of Isaiah, Israel and the world is here clearly expressed. To attribute what will happen to this One, by the arm of Yahweh, seems beyond belief. It will go against all that men had expected of the Davidic king and Servant. But note carefully this reference to the ‘arm of Yahweh'. The arm of Yahweh usually refers to Yahweh acting in power to bring about His purposes. And then men expected thunder, and lightning, and extraordinary happenings, not this trail of humiliation and death. And yet was ever greater power revealed than this? For this One Who comes is the Arm of Yahweh being expressed in all His power. None who stood before the cross could even have faintly conceived what was being accomplished there. It has been studied for over two thousand years, and yet we only have a faint conception of it. What happened there was so immense that no one can grasp it. All we can understand are the outskirts of His ways.
Note the use of ‘we', constantly used with its equivalents through to Isaiah 53:6. It is applying all that is said to man's situation. It includes Isaiah, it includes all who respond to the Servant, thus it may include the kings in Isaiah 52:13, and in the end the nations who respond.
In Isaiah 51:12 ‘the arm of Yahweh' had been called on to awake and put on strength, to smite Rahab, but what is happening here appears to be the very opposite. Who could possibly have foreseen that such a One Who was to be so humiliated could shake the world to its very foundations as the Arm of Yahweh, and smite a greater than Rahab? But He did.