I still remember how badly my mother did the dishes. Often times there was a full serving left on some of the plates! My dad and I would kid her about it quite mercilessly. Then as an adult, I realized I inherited my mother’s habit for doing the dishes poorly. The bowls and cups are clean in they’re clean on the outside aren’t they? They’re clean if they look clean aren’t they? No. The dishes are clean when they are clean…inside and out.
This is precisely the context Jesus uses for talking about personal purity. But he’s not talking about making sure the outside is clean, he’s talking about making sure the inside is clean. In fact, based on his teaching in Mark 7, we’re forced to infer that Jesus is the only way we would ever become clean.