I would say that it was natural law, which God established.
The ancient Romans build an extremely disciplined and effective society with a high standard of personal integrity.
The fear of the God of Abraham is a powerful incentive to building a disciplined community, but so is a unsentimental acceptance of the reality He created.
The Romans had the latter.
if homosexuality and orgies and sadistic perversions is your idea of high personal integrity, then i pass... they collapsed after few hundred years and completely disappeared. Present italians are NOT their descendants.
Abraham is entirely different story. I am his direct descendant ;-)