The Jewish approach to purity in the first century (and before) focused on the acts of the body. Thus, one was pure if the person did the right acts in the right way at the right time. For example, one person could actually hate another person, and remain pure if the hater treated the person he hated properly. Or, one person could deceive another and still be pure if the deceitful person deceived in the proper way.
In this concept of purity, what was inside a person did not matter if the person acted appropriately. What he actually felt, his motives, his reasoning behind his behavior, etc., were unimportant if he acted appropriately. As examples, his feelings for another mans wife were not important if he acted properly toward the woman. Or, he may be greed-filled over anothers possessions, but it did not matter if the greed did not control his actions. Only ones actions affected his religious purity.
Jesus teachings focused on what was within the person. That affected the persons purity. Thus, Jesus emphasized one was not made pure by what he ate, but by his internal motives and emotions. The true origin of an evil act is an evil heart. A cup washed only on the outside is still dirty. A tomb looked outwardly beautiful, but it was inwardly vile. Purity involved the persons inward thoughts as well as outward acts.
Peter had heard for so long the outward emphasis that he did not understand Jesus point. As an explanation, Jesus said this: Are you still lacking in understanding also? Do you not understand that everything that goes into the mouth passes into the stomach, and is eliminated? But the things that proceed out of the mouth come from the heart, and those defile the man. For out of the heart come evil thoughts, murders, adulteries, fornications, thefts, false witness, slanders. These are the things which defile the man; but to eat with unwashed hands does not defile the man. Matthew 15:16-20 (NASB)
To be pure, should I focus on the inside or the outside? Both! May your actions always reflect your actual person! Righteousness results from righteous acts and motives!
Link to other Writings of David Chadwell