THe first reading consists in extracts from Malachi 1:14- 2:10 which is really an unattributed book because the name of it just means ‘my spokesperson’ i.e. God’s prophet. It seems to date from a time when the Jews are back in Jerusalem after their years of exile in Jerusalem. So the leaders should be busy re-establishing their good and wholesome religious practices free from pagan influence; but it seems that the priests are not doing this task well and are losing the respect of people because of this; so the prophet must speak the harsh words of God against them and it seems that they will lose the respect of the ordinary people of God.
The second reading is 1 Thessalonians 2:7-9 with verse 13 added (“We also constantly give thanks to God for this, that when you received the word of God that you heard from us, you accepted it not as a human word but as what it really is, God’s word, which is also at work in you believers”). Paul reminds them how committed he was to them when he was first with them and how much he loved and cared for them, asking for nothing in return. He made some money for himself with his profession as a tentmaker.
For the gospel we have Matthew Chapter 23 verses 1 to 12 which is when his story of the life of Jesus comes towards the climax because of Jesus’ opposition to the the leaders of the Jewish religion at that time. This criticism from Jesus of the Pharisees was particularly suited to the Jewish Christians that Matthew chiefly addresses because about this time when the Temple was destroyed the Pharisees still thought of their themselves as the important leaders of the Jews and regarded the converts to Christianity with disdain and so they had to start their own gatherings for religious services. But for Jesus this was the inevitable climax of what he had come to say and do – to promote love of others as fellow human beings and to offer companionship with all at whatever cost.
see Jeffs Jottings – Not religiously