The way I think of that is this analogy. Lets say, I as a born again christian decided one day that since God didnt do what I expected of Him or what not, and I chose to dig my heals in and say, everything You, (meaning Christ) has done in my life, I declare that you are not God those things really didnt happen or mean anything after all, and I no longer want you in my life and I will never again beleive you are the Son of God, ect. and I never repent of disowning and denying that Jesus Christ is Lord, and that the works of the Holy Spirit were NOT of Him, I believe that may qualify as the unpardinable sin. BUT, than the question for me would be, ‘was I really ever saved to begin with?’ The Sheperd will always leave the herd and go after that one sheep. But if that one sheep continues to disobey and continues to run away and be defiant, I wonder if that sheep was ever really a sheep.
I dont know if I made any sense here at all, but I tried! Great topic though!