At one time backslide, backsliding, backslider were quite common:
The primary sense was from the outset religious—“apostate”— (see various translations of chapter 14, verse 14 of the Book of Proverbs, including the King James translation, but it has long been used for return to less specifically theological misfeasances, as in this from The Bristol Temperance Herald for January, 1855:
And it's still current; you don't get much hipper than Seinfeld, when Elaine 'bumps into' her ex-boyfriend:
PUDDY: Hey Benes, How are you?
ELAINE: I’m doing great.
PUDDY: Great. (pauses) See ya.
JERRY: Well, that’s it. You two are back together.
JERRY: The bump into. The bump into always leads to the backslide.
ELAINE: David and I will not be getting back together.
JERRY: Elaine, breaking up is like knocking over a coke machine. You can’t do it in one push, you got to rock it back and forth a few times, and then it goes over.
GEORGE: That’s beautiful.
ELAINE: What about you? You were even engaged, and you cut it off just like that.
JERRY: That’s different. I didn’t have feelings for those people. But you, you’ll backslide