Today's Gospel (Mt. 7:1-13) goes very well with Luke's parable of the Good Samaritan. There is a kind of twofold message here. The obvious one is that Jesus doesn't let us play games with the Word of God or shield ourselves from its call through clever interpretations that de-claw it. But also, Jesus is hinting that you can't always tell by appearances who is really keeping the Word and Law of God.
I think we do have the tendency to re-interpret the Word of God to make it less challenging, less of a declaration of sovereignty that clearly establishes the order of things (who is God and who is not). Jesus does not tolerate customs, no matter how venerable, that vitiate the Word of God. This might be the invitation to an examen of consciousness: What customs do I take refuge in to protect myself from the power of God's call? A clue might be the level of passion or engagement with which I defend things that are good, but not ultimate in themselves. It is very, very easy to "nullify the Word of God" for the sake of some beloved custom or other! In a way, every reform movement in Church history has been in answer to this kind of compromise.