Sometimes, I get confused. I wonder whether some people are truly saved in the first place. Can one just "appear" to be saved but not really sincere in the faith? Is there a difference between genuine Christians and those who merely dabble in Christianity for a time (1 John 2:19; Romans 8: 38, 39).
The Bible says that true Christians don't remain unrepentant. Yes, a true Christian may have moments of weakness or temporary lapse of faith. They may stumble, but not for long, they return again to the Lord. So, if one still intentionally sins or persists in disobedience against God over time, what is that? May it be that one merely tasted God's grace but have not truly believed?
One time, a Filipino bestseller book writer (Nelson D.) wrote me a note, reflecting on the behavior of a persistent adulterer who claims to be a believer. He said, "... it is getting harder to reconcile her behavior with her professing being a Christian. In matthew 18:17, Jesus taught that if a believer still would not repent even after being told of his sin by the church, he is to be treated as a pagan and a tax collector, ie. as if he is an unbeliever."
"If they have escaped the corruption of the world by knowing our Lord and Savior Jesus Christ and are again entangled in it and overcome, they are worse off at the end than they were at the beginning. It would have been better for them not to have known the way of righteousness than to have known it and then turn their backs on the sacred command that was passed on to them. Of them the proverbs are true: 'A dog returns to its vomit,' and, 'A sow that is washed goes back to her wallowing in the mud.' " (2 Peter 2:20-22)