By your standard no one who commits an act of sin after they profess Christ as Savior is/remains saved.
For every little white lie you tell, or maybe you break the law and exceed the speed limit, or maybe you commit a little lust in your heart....in your opinion you are not saved.
That's the standard you're holding Duggar to. If your standards are to be used, then no one is saved or could ever be saved and remain saved. It would be a continuous cycle over and over and over again always wondering if you were or were not saved.
No, I am not saying that.
All have sinned and have come short of the glory of God, and no one can go through life without sinning, saved or unsaved.
The point is that one sin does not remove salvation, but Baptists/Calvinists can’t sit back though and say:
“We don’t know how many sins it takes to show that a person was never saved in the first place.”
Because it they say that no one can know at what point a person finally shows they were never saved in the first place, then anyone can go around saying they are still saved, just “out of fellowship with Christ” despite what they are doing and you will have CHAOS.