Summary: How do we escape God's righteous judgment if we are accountable to God for thinking about it?
The Affairs of the Heart
At the beginning of last week’s sermon (“More righteousness Needed, Please!”) we saw just how critical that verse 20 is to the interpretation of the Sermon on the Mount in general and this portion of the sermon in particular. It serves as a transition from Jesus statement that He came to fulfill all of the Scripture and not just the Law as well as the warning for those who teach the Scriptures to do likewise, or else. This verse singles out the teaching of the Pharisees as being deficient. The Pharisees were not merely guilty of hypocrisy. The problem is not that they taught the truth but failed to live up to it. Instead, they failed to teach the counsel of God and mixed human wisdom and understanding with the Word of God as though the two were equal. So Jesus demand for righteousness was more than simply being a better Pharisee. The righteousness we need has to come from without and not within. This is why Jesus came to become the atonement for our sin. He is the righteousness we truly need.
Exposition of the Text
Like the commandment “do not murder”, the commandment “do not commit adultery” is straight from the Bible without any human addition. The Ten Commandments states this. So Jesus who came to fulfill all the Law as well as the prophets, every jot and tittle of it, could not in any way change this truth. The act of adultery is still adultery and offensive to God. It is also offensive to Jesus who came to do God’s will. In this the Pharisees were entirely correct.
But as we noted in last week’s sermon that these verses were a demonstration of the insufficient righteousness of the Scribes and Pharisees. There are not additions to what God said about adultery, so how could this be a demonstration of the failure of the Pharisaic teaching?
Jesus does not condemn the idea that the Pharisees were against adultery. The deficiency of the Pharisees was that they did not go far enough. They saw the Law as an external observance only. In other words, as long as they did not act on the desires of the heart, they were OK. Jesus points out this deficiency by explaining the fullness of God’s intention for this commandment. He does this by emphatically using the pronoun “I” rather than just letting the verb alone express it. He is putting what He is saying on par with Scripture. With this divine authority, he demonstrates the failure of the teaching of the Scribes and Pharisees.
Jesus’ words are simply devastating. A man who has looked after a woman to lust after her has already committed adultery with her in his heart. The reason that there is the Ten Commandments in the first place is because the hearts of men and women are desperately wicked. Just like actual murder starts with hate in one’s heart, adultery begins with lust. The best the Law can do is to express that this activity is contrary to the will of God and offensive to His holiness as well as act as some sort of restraint to the committing of the act.