It is not our misdeeds which accuse us before God, but our hearts, fractured and divided as they are. Jesus insists that we go deeper than our external deeds. The vital question is what is going on in our hearts, our thoughts and motivations? The teaching is presented using various examples, presented sometimes with great simplicity, other times with irony and wit.
If you choose, you can keep the commandments, and to act faithfully is a matter of your own choice. He has placed before you fire and water;stretch out your hand for whichever you choose. Before each person are life and death, and whichever one chooses will be given.
For great is the wisdom of the Lord; he is mighty in power and sees everything; his eyes are on those who fear him,and he knows every human action. He has not commanded anyone to be wicked, and he has not given anyone permission to sin.
They are happy whose life is blameless,
who follow God's law!
They are happy those who do his will,
seeking him with all their hearts. (R./)
You have laid down your precepts
to be obeyed with care.
May my footsteps be firm
to obey your statutes. (R./)
Bless your servant and I shall live
and obey your word.
Open my eyes that I may consider
the wonders of you law. (R./)
Teach me the demands of your statutes
and I will keep them to the end.
Train me to observe your law,
to keep it with my heart. (R./)
Yet among the mature we do impart wisdom, although it is not a wisdom of this age or of the rulers of this age, who are doomed to pass away. But we impart a secret and hidden wisdom of God, which God decreed before the ages for our glorification. None of the rulers of this age understood this; for if they had, they would not have crucified the Lord of glory. But, as it is written, "What no eye has seen, nor ear heard, nor the heart of man conceived, what God has prepared for those who love him," God has revealed to us through the Spirit. For the Spirit searches everything, even the depths of God.
Jesus said to his disciples:
"Do not think that I have come to abolish the law or the prophets; I have come not to abolish but to fulfill. For truly I tell you, until heaven and earth pass away, not one letter, not one stroke of a letter, will pass from the law until all is accomplished. Therefore, whoever breaks one of the least of these commandments, and teaches others to do the same, will be called least in the kingdom of heaven; but whoever does them and teaches them will be called great in the kingdom of heaven. For I tell you,unless your righteousness exceeds that of the scribes and Pharisees, you will never enter the kingdom of heaven.
"You have heard that it was said to those of ancient times, 'You shall not murder'; and 'whoever murders shall be liable to judgment.' But I say to you that if you are angry with a brother or sister, you will be liable to judgment; and if you insult a brother or sister, you will be liable to the council; and if you say, 'You fool,' you will be liable to the hell of fire. So when you are offering your gift at the altar, if you remember that your brother or sister has something against you, leave your gift there before the altar and go; first be reconciled to your brother or sister, and then come and offer your gift. Come to terms quickly with your accuser while you are on the way to court with him, or your accuser may hand you over to the judge, and the judge to the guard, and you will be thrown into prison. Truly I tell you, you will never get out until you have paid the last penny.
"You have heard that it was said, 'You shall not commit adultery.' But I say to you that everyone who looks at a woman with lust has already committed adultery with her in his heart. If your right eye causes you to sin, tear it out and throw it away; it is better for you to lose one of your members than for your whole body to be thrown into hell. And if your right hand causes you to sin, cut it off and throw it away; it is better for you to lose one of your members than for your whole body to go into hell. "It was also said, 'Whoever divorces his wife, let him give her a certificate of divorce.' But I say to you that anyone who divorces his wife, except on the ground of unchastity, causes her to commit adultery; and whoever marries a divorced woman commits adultery.
"Again, you have heard that it was said to those of ancient times, 'You shall not swear falsely, but carry out the vows you have made to the Lord.' But I say to you, Do not swear at all, either by heaven, for it is the throne of God, or by the earth, for it is his footstool, or by Jerusalem, for it is the city of the great King. And do not swear by your head, for you cannot make one hair white or black. Let your word be 'Yes, Yes' or 'No, No'; anything more than this comes from the evil one.
We notice a potentially fruitful tension between the Gospel and the first reading from Sirach. While Jesus makes the commandments even more demanding, Sirach claims that we can keep the commandments if only we really want to. Both readings are very direct and there's no missing the message.
One approach to today's Scriptures would be to take them as pointers and ideals for Christian morality. Jesus forbids not merely murder, as the most extreme form of disregard for another person, but also lesser forms of injuring others. What unites the three faults he lists (losing one's temper, using insulting names and of refusing to forgive) is that in each case the other's feelings are trampled underfoot. The importance of forgiveness is shown by the fact that it comes before strictly religious duties, and presumably the same priority is assigned to the other two matters. So the point Jesus makes is that one must respect not simply people's right to life but also their right to dignity and self-respect.
Then he speaks about sexual purity, but broadening it out to purity of intention in general. A mere legal observance is insufficient for Jesus. The words about self mutilation have never been taken literally by the Church. They are like a parable, to vividly express the disastrous effects of sin. The correction he makes of the Old Law excludes an abuse tolerated by Moses, namely for a man to remarry after divorcing his wife. The meaning of the exception-clause ("except on the ground of unchastity") is debatable, but it may refer to a previous marriage that was prohibited by Jewish laws. The only "divorce" is where no real marriage existed, and Jesus was declaring the permanence of the marriage bond, as in Genesis "the two shall become one flesh" -- a loving, interdependent unity.
The prohibition of oaths has not been taken as literally by the Catholic Church as it has by some other Christians. Jesus held that oaths should not be necessary at all, if there is a general a atmosphere of trust and truth-telling. In such a society reinforcement by oaths would not be needed. This it is an atmosphere of openness and mutual confidence which Jesus promoted. What he teaches by his corrections of the Law is a morality of values held from the heart.