Albert Barnes Commentary 2 Chronicles 25:14

"Now it came to pass, after that Amaziah was come from the slaughter of the Edomites, that he brought the gods of the children of Seir, and set them up to be his gods, and bowed down himself before them, and burned incense unto them." — 2 Chronicles 25:14 (ASV)

The practice of carrying off the images of the gods from a conquered country or city as trophies of victory was common among the nations of the East.

For some, like the Romans, the purpose was worship. This was especially true when the gods were already worshipped by the conquering nation and the images were considered to be especially sacred.