Up to a point you are correct.
The ancient Egyptians were considered very pious (as evidenced also by their huge temples and funerary structures) but even they had many different ruling dynasties.
But at the same time it does need to fit.
If people support you because of divine right, then getting rid of the priests altogether is not that smart, unless you have a well-thought out plan, and even then it's difficult (as the case of Ankhenaten shows).
If you attempt to keep the same basic order as the person you are replacing, then you'll need to keep the power structure but perhaps change a few people in key positions. So you can replace the high priest with your new high priest (after the old one accidentally gets pushed out of a window) but not abolish priesthood itself.
You can also completely replace the old order with a new one.
In the game, the ruler is, by divine order, female. To replace that with a male would, I think, be difficult. So Shani could possibly become queen, but not Zaton (unless he shaves himself and puts on a wig
).
Replacing the old order completely, e.g. by allying with the Decayed or the Hive is of course also possible but I don't think that's ultimately in Zaton's best interest.
