What you describe is apostasy and there is no return. So someone cannot one day be saved, then unsaved, saved again, unsaved again, back to saved again as your theology teaches.
And Scriptures do not teach what you propose. Other than describing the difference between an adopted child of God and apostate:
Hebrews 6: NASB
7For ground that drinks the rain which often falls on it and brings forth vegetation useful to those for whose sake it is also tilled, receives a blessing from God;
8but if it yields thorns and thistles, it is worthless and close to being cursed, and it ends up being burned.