I appreciate you brother, agree with most of what your post but, sorry, if you read the parable about the seeds I think it's clear you can walk away from God's grace. The prodigal son, same situation. It's judging to say they were not genuine in the first place.
I think I mentioned a pastor I had sat under who left his wife for his music leader. Devastated his family,three grown children starting their own families. He took off and has remarried this woman and taken on her children and started a whole new life. Was he never saved?
You shall know them by their fruit. Sounds like rotten fruit to me. Just because someone is a pastor does not automatically mean they are saved.
As for the prodigal son. All three parables in Luke 15 were in
rebuke to the Pharisees and scribes who complained, saying, “This Man receives sinners and eats with them." Those who believe that salvation can be lost will use the parable of the prodigal son to prove that believers can lose their salvation by arguing that the prodigal son was spiritually alive, then spiritually died (lost his salvation) and was spiritually alive again (regained his salvation) from Luke 15:32 based on certain translations which read: ..thy brother was dead, and is alive AGAIN (KJV) ..for your brother was dead and is alive AGAIN (NKJV) ..this brother of yours was dead and is alive AGAIN (NIV)
Yet others will argue that in this parable, being made "alive AGAIN" foreshadows the "born AGAIN" experience that Jesus spoke of in John 3:3. Of course Jesus wasn't talking about being born again spiritually again and again. We are born once physically and born "again" once spiritually.
I find it interesting that certain translations of Luke 15:32 simply say your brother
was dead, and is alive; he was lost, and is found (ESV); your brother
was dead, but now he is alive. He was lost, but now he is found (NCV); this brother of yours
was dead and has come to life; he was lost and has been found (NRS); this brother of yours
was dead and has begun to live, and was lost and has been found. (NASB)