Interestingly, of the three "weightier matters" Christ says to focus on—judgment, mercy, and faith—only one is even mentioned in the Ten Commandments. Mercy is not listed as one of the Ten or emphasized as a major tenet but as a blessing from God to the thousands who keep His law (Exodus 20:6).
How then, do these three virtues carry such weight with the law? The Pharisees were in horrendous spiritual condition. Notice that Christ did not simply say, "You are breaking the law—keep it!" They had the law, and they allegedly kept it, ever so minutely. The problem was that they had completely lost the meaning and purpose of the law! Rather than it being a joy and benefit to them, it had become a burden grievous to be borne and unhealthy to their spiritual state.
God intends the law to be "the law of liberty" (James 1:25; 2:12). If a person looks into it and obeys, he is liberated from guilt, shame, feelings of worthlessness, self-pity, abandonment, and loneliness. In short, we can only obtain joy and happiness when we keep the law with God's intended spirit and attitude. Any other use of the law or the breaking of it leads to negative effects that preclude joy and happiness.
They had taken what Jesus and His Father had instituted as a blessing and turned it into a curse. Paul, "a Pharisee, the son of a Pharisee" (Acts 23:6) recognized how the law could become an enemy: "And the commandment, which was to bring life, I found to bring death" (Romans 7:10). When the law is applied wrongly, the consequences are always destructive.
The scribes and Pharisees used the law on others like a club and perverted it for their own selfish gain. "Pure and undefiled religion before God and the Father is this: to visit orphans and widows in their trouble" (James 1:27). How could anyone, by any stretch of the imagination, reason a way to turn this around to the point he could turn widows and orphans out of their homes, then stand in the streets as if righteous, making long prayers to God?
Is it any wonder Christ denounces them so harshly? Considering the content and repetition in His vilification, Jesus Christ is as incensed at them as perhaps anyone He ever addresses in the Bible, Old or New Testament. After calling them snakes in Matthew 23:33, He questions if there is any way they can escape eternal damnation!
Yet in His righteous anger, He still gives them insight on how to correct their course, to put them back on track regarding the spirit and attitude necessary to keep the law properly. Christ intends His instruction to cause us to think through three basic elements of the purpose of that law and how it should work to man's good.
To the Pharisees, He did not explain the relationship of judgment, mercy, and faith to the law. Why cast His pearls before swine? But if they would make the effort, He gave them a clue about how to straighten out their thinking. In so doing, they would re-establish the law's purpose and meaning and gain correct perspective in how to keep it. History shows they did not take the hint.