In my understanding, if you don't understand the simple and clear meaning of Mark 7:15, which is that neither food or anything else one puts in their body makes them unclean, as per the Jewish law, but the sins such as listed in Mark 7, then you don't understand it.
"20 He went on: “What comes out of a person is what defiles them. 21 For it is from within, out of a person’s heart, that evil thoughts come—sexual immorality, theft, murder, 22 adultery, greed, malice, deceit, lewdness, envy, slander, arrogance and folly. 23 All these evils come from inside and defile a person.” - Mark 7:20-23
"20 He went on: “What comes out of a person is what defiles them. 21 For it is from within, out of a person’s heart, that evil thoughts come—sexual immorality, theft, murder, 22 adultery, greed, malice, deceit, lewdness, envy, slander, arrogance and folly. 23 All these evils come from inside and defile a person.” - Mark 7:20-23