This could be so easily resolved if the cultist would simply say that it’s all about a point of view. From the temporal point of view, someone who claims to have faith may or may not.
But those whose names are written in the Lamb’s Book of Life that he has promised he shall never blot out? Eternal security. It can’t not be, because God wrote the book.
But since God knows those names and we do not, we should nevertheless avoid sin not just for reasons we have listed, but because from a temporal POV, we might ruin potential salvation with unrepentance.
You could argue against that, but it took me all of 5 seconds to come up with, if a cultist was TRULY speaking in love.
But since the apparent motive is to strut around and boast about how much better he is than us because he (doesn’t actually) keep a Sabbath Commandment that was already fulfilled, this will not happen.
… but then you aren’t emotionally unbalanced and under authoritarian control, like say a cultist would be.
The bottom line is that a cultist is gonna cult.
Because they are captured by the cult they can’t seek truth.
Because they have the joy sucked out of them, their remaining major emotion is anger against the joyful.
Because they are unaccepted by God and always a misstep away from hell, they are envious and in denial of those “accepted in the Beloved.”
It’s a trap. The best we can do is pray.