In the Roman Catholic tradition, St. Michael is often appealed to for aid "against the wickedness and snares of the Devil". And aside from being referred to as a serpent, Satan (who, in my campaign, would not be a devil, but The Devil) is also referred to as 'the dragon'.
According to the Book of Revelations 12:7-9 it is stated that:
"...there was war in heaven. Michael and his angels fought against the dragon, and the dragon and his angels fought back. But he was not strong enough, and they lost their place in heaven."
Note the definite article 'the'. Much like 'The Devil', 'The Dragon' seems to be another term used to reference 'The Adversary'.
In any case, I think it's a great reason to have images, like the one below, be plastered on the walls of the temples of Enigmundia -- at least those temples consecrated to the Pio Famila.
|A mosaic in the Basilica di San Marco.|
Photo taken by Carolina Victory (from her Flickr album).
This seems to imply that the term dragon is (a) generally used in a derogatory manner; or (b) all angels, archangels, thrones, powers, principalities, etc. have a form in the material realm as a dragon -- but is a form associated with unstoppable wrath and terrible power.
For a game setting, I'd choose the both options!