In the 1990s British sitcom Keeping up Appearances, Hyacinth Bucket, who insists on her surname being pronounced Bouquet, is a snob despite her family being the kind of person she looks down on. The comedy comes from Mrs Bucket getting into embarrassing predicaments in each episode.

The Gospel of Matthew is written as a series of six narrative sections, telling the story of Jesus’ life, interspersed with five sections of teaching. The beginning of the Gospel links back into the past of the Old Testament. This, the last of the teaching sections, links forward to the future. Advent is a time when we look forward to the return of Christ.
Woe 5 They were clean outside but filthy inside
‘Woe to you, teachers of the law and Pharisees, you hypocrites! You clean the outside of the cup and dish, but inside they are full of greed and self-indulgence. 26 Blind Pharisee! First clean the inside of the cup and dish, and then the outside also will be clean.
Matthew 23:25-26
Blessed are the pure in heart,
Matthew 5:8 NIV UK
for they will see God.
The Pharisees presented an appearance of being ‘clean’ (self-restrained, not involved in carnal matters), yet they were dirty inside: they seethed with hidden worldly desires, carnality. They were full of greed and self-indulgence. Like Hyacinth Bucket they were concerned the outward appearance.
You will know what is inside a cup when you knock up against it. If it is full of soup coffee will not spill out. It is the same with people, you can see what you are like when you rub them up the wrong way. Social media has lots of examples: When someone says they disagree with you it is not usually a personal slur, often it is a request to debate it openly. The same with when you see someone posting false information, point them to the correct information and credit your sources. Sadly social (sic) media often does not do this, disagree with some people and they reply with a personal attack. Someone has said something you know is false, look at the replies, have they already been corrected? If so do not dogpile, (slang for lots of people piling on in an online discussion) dogpiling is a form of abuse, just leave it.
Jesus said that the pure in heart will see God. This does not mean that those who are not pure in heart will not see God, there is always repentance, which is the first thing Jesus preached when starting his ministry and the first thing the disciples preached on the day of Pentecost. They were so full of the Holy Spirit that they preached repentance.
Jesus is holding back. He is not saying that they are cursed, as would usually be said in covenants from the Biblical period, he says woe to you. He is giving the opportunity for repentance, but he is still putting it straight down the line, religious leaders who are making an outward show of how good they are outwardly and have not repented will not see God. The respect of the people is what they were seeking, they have already got their reward. After all Jesus had already preached, “So when you give to the needy, do not announce it with trumpets, as the hypocrites do in the synagogues and on the streets, to be honoured by others. Truly I tell you, they have received their reward in full.” (Matthew 6:2)
The Pharisees loved a show. They would in only a few days tome be amongst the religious leaders who would refuse to enter the house of Pontius Pilate, the Roman governor. “Look at us,” their actions said, “we are not going to make ourselves impure at Passover.” Yet on the inside their motivation was to get an innocent man executed. You can’t get more clean on the outside and dirty on the inside than that, can you?
Don’t think that it is as bad as it gets, Jesus has only started to escalate things, as the next parts of this passage will show…