In my daily vocation I spend a lot of time and energy helping companies and their individual employees measure and improve the quality of the customer service they deliver in daily interactions with customers. It's been an interesting lesson in human nature. I always approach my role as coach and encourager. If a person is open and willing to change, then the process is generally a lot of fun. It's a win-win-win for client, customer, and coach. There are, however, always those who stalwartly fight the process. A few people will always refuse to change, build up anger, and spread a contagious bad attitude.
One of the things that I've learned in years on the job is that encouragement and positive reinforcement only work to change behavior with a certain segment of the population. There are some who will only change if and when they feel the fear or consequences of negative reinforcement. Sad, but true.
Isn't it interesting that a considerable amount of God's message is dedicated to warning that there are negative consequences to our unchecked poor choices and bad behavior? I would love it if God could get away with simply spouting encouraging platitudes and inspirational epithets. No matter how much we want positive change to be motivated simply by dangling a carrot in front of us, the truth is that some will only respond to a swift stick on the backside.
God's message to us, and His work in our lives, is a mixture of both.