Nicene and Post-Nicene Fathers, Vol. II:
City of God: Chapter 28

Chapter 28.—Whether the Worship of the Gods Has Been of Service to the Romans in Obtaining and Extending the Empire.

Therefore such gods, who are propitiated by such honors, or rather are impeached by them (for it is a greater crime to delight in having such things said of them falsely, than even if they could be said truly), could never by any means have been able to increase and preserve the Roman empire.  For if they could have done it, they would rather have bestowed so grand a gift on the Greeks, who, in this kind of divine things,—that is, in scenic plays,—have worshipped them more honorably and worthily, although they have not exempted themselves from those slanders of the poets, by whom they saw the gods torn in pieces, giving them licence to ill-use any man they pleased, and have not deemed the scenic players themselves to be base, but have held them worthy even of distinguished honor.  But just as the Romans were able to have gold money, although they did not worship a god Aurinus, so also they could have silver and brass coin, and yet worship neither Argentinus nor his father Aesculanus; and so of all the rest, which it would be irksome for me to detail.  It follows, therefore, both that they could not by any means attain such dominion if the true God was unwilling; and that if these gods, false and many, were unknown or contemned, and He alone was known and worshipped with sincere faith and virtue, they would both have a better kingdom here, whatever might be its extent, and whether they might have one here or not, would afterwards receive an eternal kingdom.