A couple years ago, I was in a Bible reading going through Leviticus. Someone brought up Mark 7:14–23 with respect to the dietary laws. That sparked some discussion...
When we read through the Levitical law with the Lord's words in mind – it's what comes out of us that defiles us, not what goes in – we begin to see that even when we're so careful about what we take in, what comes out still defiles us (Deuteronomy 23:12–14).
Think about that! Take every precaution we can to only allow what's pure in, and what comes out will still defile. That's worth thinking about.