Nebuchadnezzar was Belshazzar"s grandfather rather than his father, but the original language commonly used "father" in the sense of ancestor. [source][source][source]
"Neither in Hebrew, nor in Chaldee, is there any word for "grandfather," "grandson." Forefathers are called "fathers" or "fathers" fathers." But a single grandfather, or forefather, is never called "father"s father" but always "father" only." [1][source]
Evidently the vessels taken from the Jerusalem temple had been stored as trophies of war and not used previously (cf. Daniel 1:2). Their presence in the warehouses of Babylon was sufficient humiliation of Yahweh who, in the minds of the Babylonians, could not prevent their theft. However, using these vessels in praise of Babylon"s gods was even more sacrilegious than just possessing them. [source][source][source]
"Have you noticed how in recent years the world has stepped into the "sanctuary" of faith and laid its ruthless hands on some of the things we hold most sacred? Our day has seen this impious sacrilege carried into many other realms, as well. Is God unmindful of this? Will He not visit for such defiance?" [2][source]
Again, as in chapters3,4 , a pagan king set himself up as superior to Yahweh. Perhaps Belshazzar did what he did to strengthen nationalistic pride among the Babylonians as well. [source][source][source]
The description of Babylon"s gods as gold, silver, bronze, iron, wood, and stone probably reflects the Hebrew perspective of the writer (cf. Daniel 5:23). For the Israelites, the gods that Belshazzar honored were no gods at all. [source][source][source]