Belshazzar does not submit himself before the Most High God, whom Daniel serves and depends upon for all things. As a result, Belshazzar's reign comes to a sudden end and we are challenged to repent of any defiant response to God.
The book of Daniel speaks to God's people throughout their history, starting with the Babylonian exiles, continuing through the years of the Greek and Roman empires, and to the Christian church throughout the centuries across the globe. It is also particularly relevant in our time.