If serpent mythology was in fact entwined with Passiflora mythology, as Mayan, Incan & Aztec snake-headed vine-image lends one to suspect, it was a large myth indeed, as the sacredness of serpents in Native American mythology is extravagant & signal, though I will not outline it here. Enough to say that much of the serpent mythology is cthonic in nature, even as is the central Christian myth. So it could all be easily Christianized by the converted aboriginal peoples themselves, just as medieval Christians took the Caduceus representing either the Greek Gods of Medicine & of Speed, reinterpreting the serpent on the sword as Jesus on the Cross (citing also the brass pole-serpent established by Moses). At the same time, finding the serpent image a little unsettling, the symbol was frequently changed from a snake into a vine that uses a cross as a trellis. Such Christian symbols would not have been completely alien to aboriginal peoples, whose own myths held so many parallels.