Matthew 15:11 What goes into someone’s mouth does not defile them, but what comes out of their mouth, that is what defiles them.
How often have you had some sort of bad thoughts about someone just because of what they eat or how they eat? It’s disturbing even if it was only once!
Humans do tend to judge others all the time over silly things and Jesus points this out by saying it is not what goes in our mouths that makes us bad but what comes out of them!
Most of us find it hard to stop saying the wrong things; things which will hurt others or which are just plain evil. They just seem to slip out.