Isaiah uses poetic language to describe the plight of the house of Jacob. He says that God has forsaken his people. That is correct in emphasis, and perhaps in the evidence of the short term, but it is not true of God’s overall faithfulness to his part of the covenant.
The conditions Isaiah describe indicate the ways in which Israel has allowed outside influences to lead them astray. They have received influences from outsiders to the east, and rather than listen to Jehovah’s prophets, they listen to common soothsayers. When Isaiah chides them for listening to soothsayers “like the Philistines,” it is intended to be an insult.
Nevertheless, Isaiah understands why Israel is interested in these influences. The other nations are rich and powerful. There is no end to their treasures. There is no end to their military might.
However, Isaiah words that in addition to their lands being full of silver and gold, they are also full of idols. When Isaiah says that they worship the work of their own hands, he is suggesting that they worship gods with no true power. Isaiah mentions these idols and gods because inviting the alluring cultural advantages of wealth can bring with it those idols and foreign gods, to the detriment of remembering their true God.