Isaiah points out that the tribes of Israel, including the Jews, take pride in identifying themselves with the holy city of Jerusalem. However, the Book of Mormon version then goes on to say "but they do not stay themselves upon the God of Israel, who is the Lord of Hosts." Notice that the absence of the word "not" in the King James version almost makes the verse meaningless, but the Book of Mormon corrects this error.
3. Behold, I have declared the former things from the beginning; and they went forth out of my mouth, and I showed them. I did show them suddenly.
The Lord says in this verse that the Israelites have no excuse for not recognizing the integrity of the messages which the Lord has been giving his people from the earliest times. The Lord has revealed with unerring accuracy those things which are going to come pass long before the events transpired. 4. And I did it because I knew that thou art obstinate, and thy neck is an iron sinew, and thy brow brass;
The Lord says he went out of his way to deliberately do this because the children of Israel have been such a strong willed and obstinate people. Their necks have been so stiff and arrogant that sometimes it reminded the Lord of an iron sinew. It has been so hard to get some things through their thick heads that the Lord refers to them as having brows of brass.
5. And I have even from the beginning declared to thee; before it came to pass I showed them thee; and I showed them for fear lest thou shouldst say -- mine idol hath done them, and my graven image, and my molten image hath commanded them.
The Lord points out that those who have turned to idolatry are so anxious to attribute divine power to their images and the idols, that they will use the slightest coincidence as proof that their gods of gold or wood have provided them signs portending some great future event. That is why it has been necessary for the Lord to persuade his stubborn children of his own divine integrity by predicting events hundreds or even thousands of years before they happen. It has to be something spectacular, such as naming Cyrus a hundred years before he was born, or these foolish idolaters will attribute these great events to the commands of their graven idols or molten images.