Because during the episode where the old woman was stoned, at the part where the cult leader Patti and the Sherrif's ex wife Lori were in the diner where Patti was telling Lori that that she cant have any doubt about their movement, and by explaining how the old lady, Gladys, kept having doubt and showing emotion over her dead son, Patty took Gladys on a one day getaway from the cult life so she could clear her mind the same way Patty was doing for Lori.. Gladys ultimately gets stoned to death... Patty never outright admits to Lori that she had Gladys stoned, but if you can read between the lines, it was a clear warning and threat and threat to Lori that she doesn't want to go down the same path as Gladys and she better get with the program or else she'd end up like Gladys if her faith in their cult wavered.. Patty went as far as to even say that having doubt would burn your soul to ash.. Remember that episode ended with Gladys going into an incinerator. Im pretty sure Lori picked up on the threat too, which is why she put on that whole show with the rape whistle in front of Patty later when the reverend was preaching outside the cult house
