What about telling the truth? According to surveys, Americans lie all the time, often with no apparent reason. But in most other societies, both past and present, telling the truth has always been judged an important personal virtue. What was the problem in Jesus’ day then? It was exactly what we have been seeing all along: the corruption of the heart.

People knew they were to keep their word, as we do. Above all, they knew if they had taken an oath they were to keep it. But the rabbis focused on the specific wording of the oath, distinguishing between those that were binding and those that were not. If the Bible said, “Keep the oaths you have made to the Lord,” such oaths were clearly binding. But what about oaths that were made only “to heaven” or “by the temple” or “by one’s life”? Were such oaths binding? An entire tractate [treatise] of the Mishnah is given to distinguishing between oaths that had to be kept and those that did not. We see a reflection of this thinking in Matthew 23.16-22, where Jesus elaborates on some of these distinctions, but His point in chapter 23 is the same as here in Matthew 5: Any failure to keep one’s word is a sin before God. Hence, for the righteous man there should be no need for oaths at all. On the contrary, a righteous man’s yes should be yes, and his no should be no.

These verses do not forbid oaths under formal occasions, as in a court of law, since the Bible contains examples of such oaths. Even God takes oaths (He.6.17-19).

What about the law of retaliation? Various forms of this law date back to the ancient law code of Hammurabi (2285–2242 B.C.), but it is also expressly stated in the Old Testament in at least three places: Exodus 21.23–25; Leviticus 24.19–20; Deuteronomy 19.21. It limits recovery to the actual damage done. However, the Old Testament also forbids an individual from seeking revenge or bearing grudges: Leviticus 19.18; Proverbs 20.22; 24.29. Jesus told the people they were wrong to focus on verses that refer to revenge (though limited) and ignore those that call for a forgiving heart. The right attitude was not to insist on their rights and even to bear cheerfully many types of wrongs (vv.40-42).

Love for Enemies: -The examples that conclude Jesus’ words about the law of retaliation lead to the last of His six antitheses, the command to love our enemies. Again, the people knew that they were to love their neighbors, for that was stated clearly in Leviticus 19.18. Jesus calls it the second great commandment in Matthew 22.39, after the first, which is to “love the Lord your God with all your heart and with all your soul and with all your strength” (Dt.6.5). But if the law said, “Love your neighbor,” did that not allow hatred of our enemies by contrast? That is what some were teaching, even though the words “and hate your enemies” are found nowhere in the Bible.

Jesus teaches that the citizens of the kingdom are to love their enemies as well as their friends, because that is the way the heavenly King treats them. It is only as they display kindness to those who are evil as well as to those who are good that they will be able to demonstrate that they are the true sons and daughters of God.

Jesus’ summary is in verse 48: “Be perfect, therefore, as your heavenly Father is perfect.” This verse does not teach perfectionism, since none of us are or can be perfect in this world. But what does it teach?

William Barclay explains it by use of the meaning of the Greek word teleios (“perfect”), which describes something perfectly suited to the end for which it was created, like a full-grown adult as opposed to a person who is still a child, or a tool perfectly suited to a task. “The Greek idea of perfection is functional,” Barclay says. Harry Ironside also sees the verse as a call for impartiality, arguing, “This is perfection in the sense of the complete absence of partiality…”

Those interpretations could be on the right track, but I think D. A. Carson is wiser when he refuses to drop the idea of perfection so easily. It is true that we will never be perfect in this life, but the perfections outlined in this sermon are still those for which we should aim and that we should increasingly attain by God’s grace and power in our lives. Carson says that the form of this verse is exactly the same as Leviticus 19.2, with “holy” merely being displaced by “perfect” (“Be holy because I, the Lord your God, am holy”), and that Leviticus 19.2 is likewise urged on God’s people in the Bible.

What Jesus is saying is that the “direction in which the law has always pointed is not toward mere judicial restraints, concessions arising out of the hardness of men’s hearts, still less casuistically perversions, nor even to the ‘law of love.’ … No, it pointed rather to all the perfection of God, exemplified by the authoritative interpretation of the law bound up in the preceding antitheses. This perfection Jesus’ disciples must emulate if they are truly followers of him who fulfills the Law and the Prophets.”

Barclay is not entirely wrong when he says that we should be perfectly fitted to that for which we were created. But this is not some low standard, as if it meant only to be a well-rounded person. We were created to be like God, to aim at Christ-like character. The only way we will be able to aim at that character and achieve it is if God gives us a transformed heart.