The church is working hard to help the backsliders who have fallen back into bad habits.

backsliders 是由动词 backslide（退步、堕落）加上后缀 -er 构成的名词。backslide 由 back（向后）和 slide（滑动）组成，字面意思是"向后滑落"，比喻"退步、堕落"。backsliders 指"退步者、堕落者"，特指那些曾经改过自新但又重新陷入恶习的人。