THERE ARE THREE SECTIONS TO Isaiah 46, and each advances a distinct argument that implicitly or explicitly calls Israel to faithfulness toward the living God.
(1) In the first two verses, Isaiah mocks Babylonian gods. "Bel" means "lord" and is equivalent to Baal as a title. It was applied to Marduk, the chief god of the city of Babylon. "Nebo" was the son of Bel-Marduk. He was the patron of writing and wisdom. At the New Year festival, Bel-Marduk and Nebo were carried through the streets in a great procession to the Esagila shrine. It was the greatest religious event of the year. But Isaiah foresees a time when Bel-Marduk and Nebo bow and stoop, and the exhausted beasts of burden that have to carry them fall and stagger off into captivity (Isa. 46:1-2). This was not literally fulfilled when the Persians took over in the sixth century, for Cyrus preserved and even enhanced the status of the Babylonian gods. On the long haul, of course, Bel-Marduk and Nebo slipped into oblivion. No one worships them today. But millions of men and women still worship the God of Israel.
(2) In the next section (Isa. 46:3-7), God continues his denunciation of idolatry. Now there is a slightly novel development. God says, in effect, that idolaters have to carry their gods, and even their beasts of burden get tired; but with the true God, it is the other way around: he carries his people. It is hard not to perceive a contrast between two religions. In the one, the people do all the heavy lifting; in the other, God does it, and his people are carried by him.
(3) In the last section (Isa. 46:8-13), God rebukes his covenant people in blunt, not to say brutal, terms. They are rebels, and they have forgotten all of God's gracious and powerful ways with them when the nation was born at the time of the Exodus. There are important things for the believer to remember (Isa. 46:8-9). Probably part of their hang-up is still Cyrus. They still find it difficult to imagine that God will use a pagan king like that, rather than simply destroy him. But God insists he will summon from the east "a bird of prey" (Isa. 46:11)---almost certainly a reference to Cyrus. Whatever his purpose and plan, he will be sure to bring it to pass. The implication, of course, is that God is both sovereign and good---so stop trying to second-guess him, and trust him. "Listen to me, you stubborn-hearted, you who are far from righteousness. I am bringing my righteousness near, it is not far away; and my salvation will not be delayed" (Isa. 46:12-13).