Both of the questions asked by the exiles have been fully answered in 40:1-26:
- 40:1-11 answers the question, "Does God care?" (Has our sins separated us from God forever?) God will come in glory to renew the whole world (Isa 40:5).
- 40:12-26 answers the question, "Is God able to deliver us?" (Was God not defeated by the gods of Babylon?)
How then should God's people respond? This question is answered in 40:27-31.
- Our despair (27).
- God's greatness (28).
- Our renewal (29-31).
In 40:27 Isaiah anticipates the attitude of the exiles. They think that they are either now outside of God's vision for them ("my way is hidden") or that God has given up on them ("my cause is disregarded"). Their complaint is that God doesn't know and/or God doesn't care.
To this Isaiah responds that to think in this way is to have too low a view of God. It is to essentially not really know who God truly is. So Isaiah reminds them of who God is in 40:28-29, dealing with the Creator's endless power and wisdom in the first verse (Isa 40:28) and his wonderful desire and ability to share that power with the "weak" and the "weary" in the second (Isa 40:29). So Isaiah speaks of both the being and the person of God.
The question in 40:28 is incredulous. How could they say such things about God when they know who he is and what he is like. God knows our situation perfectly, and he can and will do something about it. The fact is that the most vigorous things in creation ("young men") cannot keep themselves going. They are not self-generating but are dependent on outside sources for their strength. God is not like that. God is self-generating. That means that he also has abundant strength to give away to those who will wait for ("hope in") him.
The theme of trust from ch.1-39 continues in Isa 40:31. This concept of trust as waiting has already appeared three times previously (Isa 8:17; 25:9; 33:2) and will appear twice more (Isa 49:23; 64:4). To "wait" on God is not simply to mark time. Rather, it is to live in confident expectation of his action on our behalf. It is to refuse to run ahead of him in trying to solve our problems for ourselves.
Just as Isaiah called on the people of his own day to trust God to solve their problems, he calls on the exiles a century or so later to do the same thing. If they are worn out and weary, hardly daring to believe that there is any future for them, the God of all strength can give them exactly what they need at the right time, whether or "soar," "run," or "walk" (Isa 40:31).
