The Devil in the Form of the "Old Gods"

I found it interesting that Sulpicious decided to have the devil show himself to Martin the guise of the "old gods" at the beginning of Section 22.  Now certainly I can see why a Christian author would choose pagan gods as disguises for the devil as they are obviously profane and diabolical by this point in time.  I can also understand why perhaps donning the image of a pagan god may work for the devil when presenting himself to the numerous heathens mentioned throughout the work, as they still believe in the the "old gods" and would be open to accepting the devil in these forms.  However, Sulpicious has the devil presenting himself in these images to "the holy man," i.e Martin.  Certainly Martin being a Christian and not believing pagan gods would have seen through such a disguise and realized immediately that the individual was not who they said they were since the pagan gods are false.  Perhaps Sulpicious decided upon such an explanation to give the devil extra devilness or perhaps even to show that he is not a very crafty devil.  We have already seen and will see again that he is hardly a persistent devil, as Martin simply brushes him off a number of times and he simply vanishes in a puff of smoke.  This is just speculation but I did find this interesting.