The original Pantheon was built in the first century BC, a time when the construction of religious buildings in Rome often represented an individual’s triumphal monument constructed to commemorate a military or political victory. 

In Rome, religion and politics were inextricably intertwined, a far cry from our modern understanding of separation of church and state. The establishment of the Pantheon was, in effect, a statement on the behalf of the Roman state that the home of all the gods of the world was in Rome.  In this way, Romans could assert that the advancement of their empire was in the best interest of all the gods of all different peoples, and therefore, Rome was the only significant capital, deserving of the entire world's submission.

This relative inclusiveness helped Rome to annex many different cultures under its rule. But it also ran them into trouble after the rise of Christianity in the following centuries. Romans were willing to take on other gods as their own, but they expected their citizens and subjects to worship the Roman pantheon of gods and goddesses, believing this was crucial to the good fortune of the Roman state. Coming out of the Jewish tradition, however, Christians of the time dismissed this intertwining of state religion and politics and refused to acknowledge the other deities, drawing the ire, and eventually persecution, of Roman authorities.