That's a very interesting take on it - if dragons are religion, then during the last long interval between the Oldtimer's Pass and the 'current' Pass, the Holds quit tithing (giving sacrifices or tribute) to the Weyrs. After all, the dragons (their gods) had abandoned them, why should they continue? There's reference to the 'Old Laws' in 'Dragonflight' as if it were an old religion that few keep anymore.
Yet when Thread starts falling again, they run right back to the dragons and their riders (the priests) for protection and start tithing again. Oddly enough, I remember in 'All the Weyrs of Pern' when one Lord Holder makes a snide comment about the Weyrs and Jaxom just about tears off his head, along with the rest of the council, who make the Lord Holder apologize. Perhaps he was speaking heresy?
The split between the Oldtimers and the present, which leads to their defection to the south, could be viewed as a great Schism in the Temple.
Yep, I'm pretty sure dragons are the religion. After all, they're never wrong, are they?