What does Mark 7:19 mean?

"Heart" is from the Greek root word kardia which refers to the source of physical and spiritual life. It is from the heart that we think, desire, and decide what we want. "Is expelled" is an overtly polite translation of a much longer Greek phrase: eis ton aphedrōna ekporeuetai. This literally means "is passed into the toilet." Without going into the details of digestion, Jesus is saying that physical food, with its clear trajectory through and out of the body, cannot cause a heart—our spiritual condition—to become defiled.

The latter half of this verse flummoxes scholars. Jesus clearly revokes the kosher dietary laws, so why did the early church struggle so much? There are two possibilities. First, this statement might be a commentary by Mark or Peter who feel the need to defend what Jesus taught Peter about kosher food on the rooftop in Acts chapter 10. Second, this may be a reference to an obscure belief, held by some scribes and Pharisees, that human excrement was ceremonially clean. Most Bible teachers believe the former, especially considering Ezekiel's reluctance to cook over human dung (Ezekiel 4:12–14). Since Mark's audience is most likely Gentiles, it's an important affirmation of the Gentile Christians' freedom from the Mosaic Law.

Jesus' statement that nothing that goes in us can defile us (Mark 7:15) is literal in regard to food but becomes a parable when applied to other areas of life. It is not a sin to hear someone swear, accidentally come upon a pornographic image, or withhold offerings from a church. Our hearts decide if these things are unclean or not. We are "unclean" if we swear with a rebellious and disrespectful attitude toward God or others. We are "unclean" if we seek out images or entertainment for the purpose of sinning. We are "unclean" if God convicts us to give and we refuse. We are also "unclean" if our hearts convince us to do something that is permitted but in a sinful way or against our convictions (Romans 14:14).