DEFILEMENT

To defile something means 'to undermine its purity, contaminate it, make it unclean'. Scripturally, it is a violation of something considered sacred (including a believer's physical body) ...

Do you not know that your bodies are temples of the Holy Spirit, who is in you, whom you have received from God? You are not your own; you were bought at a price. Therefore honor God with your bodies. 1 Corinthians 6:19-20

The Jewish elders believed that 'defilement' happened when someone ate with unwashed hands. When Christ's disciples neglected this ceremonial ritual, the following criticism came in the form of a self-serving (somewhat rhetorical) question ... 

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!” Matthew 15:1-2

The rabbinical law only required the descendants of Aaron to perform the rite of handwashing before a service. The sanctimonious religious rulers of Jesus' day had saddled the people with that which was meant exclusively for priests. 

The Lord responded by turning His attention to the assembled crowd ... Hear and understand: Not what goes into the mouth defiles a man; but what comes out of the mouth, this defiles a man. (Matthew 15:10-11)

Jesus spelled it out ... Don’t you see that whatever enters the mouth goes into the stomach and then out of the body? But the things that come out of a person’s mouth come from the heart, and these defile them. For out of the heart come evil thoughts - murder, adultery, sexual immorality, theft, false testimony, slander. These are what defile a person, but eating with unwashed hands does not defile them. (Matthew 15:17–20).

An undefiled heart bears no hypocrisy, duplicity, or hidden agenda. God has not called us to some 'lifeless' religious experience. Sadly today's church is fraught with pharisaical demands and the doctrines of men (i.e. just obey their superfluous rules the best you can).

Christians are to surrender to the Lordship of Jesus Christ, not just give Him 'lip service' ... These people draw near to Me with their mouths and honor Me with their lips, But their hearts are far from Me. (Matthew 15:8). 

The Lord is interested in 'inner' purity, not 'outward' ceremony. You must do more than 'wash your hands', pilgrim. Allow sanctification to do its work.