The Gospel reading contains the second woe against the Pharisees and the lawyers. Their attitude towards Jesus reflects their forefathers' stance towards the prophets, just as they refused to listen to Jesus.
Jesus' warning indicates that unless this generation repents, they will be charged with the accumulated responsibility for killing all the prophets. The paradox of the lawyers' misery is that even though they have the keys to enter the house of God's wisdom (Prov. 9:1), they do not enter it themselves nor allow others to do so.
This reminds us that we can easily fall victim to externalism and legalism in religion. Like the Pharisees, we tend to consider religion merely in terms of external observance of laws. Jesus wanted us to have self-knowledge to live God's Will. It is said that a true believer seeks to do good, while a legalist/lawyer seeks to avoid evil (v. 42).
This message is reiterated in the first reading wherein St Paul said in vs 27 - 28 that justification is not based on keeping the Law but through faith which is a gift from God.
"Lord, grant us the grace to be Your authentic followers and always remain grateful for the gift of faith and respond with a steadfast love for You."