Then some Pharisees and teachers of the law came to Jesus from Jerusalem and asked, "Why do your disciples break the tradition of the elders? They don't wash their hands before they eat!" (Matt. 15:1-2)"What goes into a man’s mouth does not make him ‘unclean'..."
We must ask: Who is the subject of this statement? If Jesus is speaking of the physical body - as the Pharisees are most interested in the cleanliness of the physical body - then why wouldn't eating with dirty hands - and thus ingesting dirt and bacteria - make a person 'unclean'?
Because Jesus is not speaking of the physical body here. If he was, there would be no question of whether eating with dirty hands would be unclean.
Rather, Jesus is speaking of the person within: The spirit-person who is operating the temporary physical body. This person does not become unclean if the body eats food that is contaminated.
Why? Because the spirit-person within is not the physical body. The person Jesus is speaking of - the spiritual person within - is separate from the physical body.