the subdivision of the duperies

[Chicken Sandwich]

The priests of the different religious sects . . . dread the
advance of science as witches do the approach of
daylight, and scowl on the fatal harbinger announcing
the subdivision of the duperies on which they live.

THOMAS JEFFERSON

What does the subdivision of the duperies mean? Dupery comes from dupe, which is a trick. However, in conjunction with subdivision, it doesn't make any sense. I know the literal meaning, but plugging it into this sentence, does not yield any understanding on my part.

Can anyone explain what is said here? Thanks.

[Tdol]

To me, it suggests that the author believes that science will reveal all religious sects to be sub-divisions of some basic falsehood(s), which is why they fear it.