"making a statement isn't the key to salvation."
Correct. That's why the landmark shouldn't be running around proclaiming their salvation is due to accepting (out loud) that Jesus is their lord and personal savior.
Right after that seems to come sinning such as you have never seen. Perhaps that's why it is so nauseating, to see someone that thinks they are always going to be in the "saved" condition.
NO, they are not. There will be a wide gulf in the next life between them and God, of that I am sure.
Salvation doesn't imply we will never sin again.
The landmark is merely the baptism of the spirit.
It is only nauseating for somebody who believes they can discern and judge who is saved and who isn't. Only God knows our heart.