After the shards of the Heaven-Mending Stone were stolen, the immortals of the Three Pure Orthodox Sect also exchanged thoughts among themselves.
Previously, everyone had a tacit understanding about the matter of each possessing shards of the Heaven-Mending Stone: "I know you have them, but since you don't mention it, neither will I." Therefore, in the aftermath of the theft, the three did not initially suspect anyone else.
When notable figures from the other two sects also "left the sect", everyone gradually realized: Does this situation seem similar to ours?
Upon further inquiry, it was indeed the missing Heaven-Mending Stone shards.
Although the Heaven-Mending Stone is a divine artifact with significant use in sealing and suppression, beyond that realm, it's akin to mere stone.
In other words, the mastermind behind the theft likely intended to use the Heaven-Mending Stone shards to ensure survival in the impending apocalypse.