'Cannot' in the Bible

What if some of the Jews were unfaithful? Their unfaithfulness cannot cancel God's faithfulness, can it?

For I know that nothing good lives in me, that is, in my flesh. For I have the desire to do what is right, but I cannot carry it out.

Indeed, those who are under the control of human nature cannot please God.

Let their eyes be darkened so that they cannot see, and keep their backs forever bent."