In Mark 7, Jesus says that it is not what goes into a man that defiles him but what comes out. The problem is that we have an Old Testament cleanliness code that appears to say otherwise. Is Jesus just overturning the cleanliness code?
It seems more reasonable to look more closely at what Jesus actually says. He actually says that it’s not was goes into a man that is able to defile a man, but what comes out of the heart. The point that Jesus is making, I think, is not particularly about what does or does not make someone unclean but more directly why certain things do or do not make a man unclean. The reason why people are susceptible to uncleanness is because there is something inside them that is wrong. The heart of man produces all kinds of uncleanness. That’s the fundamental problem. And that’s why making stricter washing rules (e.g. the Pharisees) really misses the point.
If being unclean is like being on fire, the Pharisees want to build a big fence around the yard to keep the fire from getting in. But Jesus says the problem is that the Pharisees are already on fire. You can build the fence as high as you like, but you’re just taking the fire with you wherever you go, incinerating everything you touch. You don’t need a bigger fence, you need a swimming pool.