I would make sure they remained in mortal terror that they could lose their salvation
But once saved always saved does sound nice to the ears.This is a mystery with what appears to be contradictions but are not.
It’s consistent with this to use an analogy that as a child you would fear to push your father too far because he might whip you to keep you in line... but that doesn’t mean he will toss you out of the house or disown you as a son. And in the end you will learn what your father has been striving to teach you, whether the easy way or the hard way.