backslide

verb (used without object), back·slid, back·slid or back·slid·den, back·slid·ing.

1. to relapse into bad habits, sinful behavior, or undesirable activities.

noun

2. an act or instance of backsliding: a backslide from his early training.

verb -slides, -sliding, -slid, -slid or -slidden

1. (intr) to lapse into bad habits or vices from a state of virtue, religious faith, etc

v.

in the religious sense, 1580s, from back (adj.) + slide (v.). Related: Backslider; backsliding (1550s).