You Whitewashed Wall

A long time ago, when I was in a customer service job, there was one annoying and mistaken client who, after long minutes of berating me for a problem of his own making, said, "If you don't do what I tell you, I'm not going to be your customer any more!" and I thoughtlessly said - out loud - "Promise?"

He may have been a jerk, but that didn't give me license to respond in kind. 

It's been over 30 years and the memory of that mistake still helps keep me from going down that road again. I developed tools to be better and allowed God to work on growing my self-control in this area (and others). But what about someone like the Apostle Paul? What happens when he makes a mistake - or a series of them? Is there any way for him to go on? Can God still use someone who has put themself in a deep hole of trouble?