Isaiah 59
v.1
Surely the arm of the Lord is not too short to save, nor his ear too dull to hear.
If our prayers are not answered, and the salvation we wait for is not wrought for us, it is not because God is weary of hearing prayer, but because we are weary of praying.
v.2
But your iniquities have separated you from your God; your sins have hidden his face from you, so that he will not hear.
The Hebrew word here is in Hiphil, meaning ‘to cause to hide.’ Kimchi and Aben Ezra understand it as causing him to hide his face; Vitringa as hiding, his face. The metaphor, says Vitringa, is not taken from a man who turns away his face from one because he does not choose to attend to what is said, but from something which comes between two persons, like a dense cloud, which hides one from the other. And, according to this, the idea is, that their sins had risen up like a thick, dark cloud between them and God, so that they had no clear view of him, and no contact with him - as a cloud hides the face of the sun from us.
It is universally true that indulgence in sin causes God to turn away his face, and to witchold mercy and compassion. He cannot pardon those who indulge in transgression, and who are unwilling to abandon the ways of sin
v.16
He saw that there was no one, he was appalled that there was no one to intervene; so his own arm worked salvation for him, and his own righteousness sustained him.
v.17
He put on righteousness as his breastplate, and the helmet of salvation on his head; he put on the garments of vengeance and wrapped himself in zeal as in a cloak.
Paul referred to this in Ephesians 6:10-18 and 1 Thessalonians 5:8.
v.19
From the west, men will fear the name of the Lord, and from the rising of the sun, they will revere his glory. For he will come like a pent-up flood that the breath of the Lord drives along.
v.21
“As for me, this is my covenant with them,” says the Lord. “My Spirit, who is on you, and my words that I have put in your mouth will not depart from your mouth, or from the mouths of your children, or from the mouths of their descendants from this time on and forever,” says the Lord.
The covenant under the Messiah, was not made especially with the prophet or his posterity, but is a promise made to the church, and here evidently refers to the true people of God: and the idea is, that the Spirit of God would be continually imparted to his people, and to their descendants forever. It is a covenant made with true believers and with their children.