How do you get this thing to work?

A preacher was making his rounds on his bicycle when he came across a little boy trying to sell a lawnmower. The preacher asked, "how much do you want for the mower?"

"I only want to earn enough so that I can buy a bicycle," the little boy replied.

The preacher considered this, then asked the little boy if he would trade the lawnmower for his bicycle. The little boy thought about it, and agreed.

The preacher took the mower and began to crank it. He pulled on the rope a few times, but the mower would not start. The preacher called the little boy over and told him, "I can't get this mower to start."

"That's because you have to cuss at it," the little boy explained.

"I can't cuss at it. It's been so long since I became a Christian, I don't even remember how to cuss," the preacher said.

The little boy replied, "that's OK, sir. Just keep pulling on that string, it will all come back to you."