There are many layers of thought in today's readings.
The reading from Numbers, follows on from a much more famous reading in which we would have 'Balams' Ass' . It appears in a common enough put down in common use today but usually by people who know nothing of the origins. If the poor donkey had not spoken then the prophet would not have become the Lord's Prophet, but would have continued to be the vassal of a human King. John the Baptist had the same risky relationship with his King - refusing to say what the king wanted to hear.
In the Gospel, Jesus confounds the Temple leaders by posing them an unanswerable question. In the following sequence of readings from Matthew's Gospel, Jesus digs in - really annoying them by pointing out to them how wrong they were about their relationship with God. This was to lead - in short course - to the crucifixtion.
If you are wondering why we have readings at the end of Advent, clearly relating to the build up to Easter - then you should also ponder why did Jesus come to Earth at all?