The basic nature of a dog is to wolf down all available food. They look for garbage, waste, and dead animals because they provide the most amount of energy intake with the least amount of effort.
A retriever has to be re-programmed to control that basic, fundamental nature of dogdom. When it goes to fetch a downed bird, it is usually bleeding. Dogs were originally programmed to devour any bleeding creature. But, the human reprogramming of the basic “dog program” into a retriever is enough to overcome that most basic of instincts.
So it is with Christians. We willingly embrace His higher, better program that keeps us from robbing and killing our neighbors for any short-term gain that such actions may provide.
Just as the faithful retriever knows that it can bring the bleeding bird back to the hunter, and has a vague awareness that its master will ensure that it be given food and housing for the rest of its life, so Christians know that by resisting earthly temptations, we may enjoy the joys of Heaven forever.