They--we--are living in a world that is far from perfect. When Jesus was asked if they should take the responsibility of getting the weeds out of the wheat field, he told them that their efforts might make things worse and, instead, the gathering, sorting, and destruction would be done for them.
This reading from Isaiah is written to people suffering from national defeat and exile, people with reason to despair. To them, the prophet delivers the message from the Lord:
I am the first and I am the last; beside me there is no god....do not fear, or be afraid; have I not told you from of old and declared it? You are my witnesses! Is there any god besides me? There is no other rock; I know not one.
In our time, and wherever we are living, we face difficulties, at times, despair. But, the solution is not totally up to us. As God promised to return Israel from its exile, as God promised to sift the wheat from the weeds, God promises to care for us.
And, God's care for us is not just for us.