Well, regarding verification of sincere saving faith, I say the following:
No one achieves moral perfection in this life (PHP 3:12), but no one who lacks divine love will reap eternal life with God (GL 6:7-8). Thus, a person who claims to be godly but who is behaving in an ungodly (unloving, untruthful) manner may be in one of the following categories:
a. a normally loving person observed during a rare moment when he/she acted uncharacteristically (PHP 3:12-16),
b. an immature Believer, who is making progress–you should have known him/her a year ago! (1CR 3:1-3, EPH 4:11-15)
c. a truthseeker who has not yet learned the correct interpretation of God’s Word (1CR 6:9-11, EPH 5:8-9), or
d. a pseudo-Christian (MT 7:21, 1JN 2:19), who may affirm morality while rejecting its divine rationale.
e. an apostate (1JN 2:19, HB 6:4-6), who once believed but became blasphemous or foolish and ship-wrecked their faith (1TM 1:19-20).
Perhaps demons could/should be listed as "f" rather than as "d".