Albert Barnes Commentary Isaiah 37:19

"and have cast their gods into the fire: for they were no gods, but the work of men`s hands, wood and stone; therefore they have destroyed them." — Isaiah 37:19 (ASV)

And have cast their gods into the fire - This seems to have been the usual policy of the Assyrians and Babylonians. It was contrary to the policy that the Romans afterward pursued, for they admitted the gods of other nations among their own, and even allowed them to have a place in the Pantheon. Their design seems not to have been to alienate the feelings of the vanquished, but to make them feel that they were a part of the same people. They supposed that a vanquished people would be conciliated with the idea that their gods were admitted to participate in the honors of those that were worshipped by the conquerors of the world.

But the policy of the Eastern conquerors was different. They usually began by removing the people themselves whom they had subdued to another land (see the note at Isaiah 36:17). They thus intended to alienate their minds as much as possible from their own country. They laid waste to everything by fire and sword, and thus destroyed their homes and all the objects of their attachment. They destroyed their temples, their groves, and their household gods. They knew well that the civil policy of the nation was founded in religion, and that to subdue them effectually, it was necessary to abolish their religion. Which was the wisest policy may indeed be questioned. Perhaps in each case the policy was well adapted to the particular end they had in view.

For they were no gods - They were not truly gods, and therefore they had no power of resistance, and it was easy to destroy them.