Now this gets tricky...how does one know when you have departed from Him. What defines this? How far do you have to depart? How do you know you've got it back?
The cross takes care of all of this. I know my sheep...
Well lets look at a couple of areas. I think some things are pretty clear, Murder, mocking God, etc are pretty serious. I think those are clear cut.
But what about all these “Self professed Christians” [Catholics, Orthodox, Protestant alike] who have been conformed to the world on the abortion issue. They are putting their souls in danger. So if one is committed to abortion agenda, they are really on the wrong way, one hopes that before they die, they will repent of their ways, so I am not condemning anyone to Hell [that is not my role], but they seem to have departed from Christ, he did not depart from them. So how would they hypothetical person get back into Communion with Christ, well, in Catholic Theology a sincere examination of conscience and confession of ones sins would be the “normative means” since in the Sacrament, God fully provides the means of Grace to restore the sinner back into communion with him.
From a protestant perspective, I can only speculate, but I would hypothesize that someone who fell away would make a sincere act of repentance via some prayer. Catholics would call this a sincere Act of Contrition and would be what one would do if they did not have access to having a Priest hear their confession. This would be