Considerest thou not - literally, Hast thou not seen, i. e., noticed?
This people - i. e., the Jews.
Thus ... - Or, and “My people they have despised,” so that they are “no more a nation” in their sight. They say that God has rejected Judah as well as Israel: and thus they despise themselves in their relation to God as His covenant-people, by regarding their national existence as about immediately to cease forever.