I got plenty of spankings as a child and not a few "Swats" from teachers (Some of whom had rather elaborate woodworking projects for paddles)up until high school. But I never had welts or bruises because of them. This pastor may have gone a little overboard.
Just my opinion.
After I was grown and married, my Dad and I were fishing one day and I was telling him some of the nonsense I did that he never knew about. He looked at me, shook his head, and said, "Boy, if I had whipped your ass once a day, if I didn't know the reason you would have."