You have heard that it was said, ‘You shall love your neighbour and hate your enemy . (v. 43)
This antithesis, the very last one, is different for two reasons, and here is one of them - "and hate your enemy" is never said in the Law, whereas all the other things that the crowds had heard said were. How can Jesus say this, then? Well, as I have commented before, the antitheses are about deepening the national law of Israel to the fullness of the moral law. In moral terms, the Israelites may have come to the conclusion that the restriction of loving one's neighbour to the fellow Israelite (see Leviticus 19) and the demands on Israel during times of war to be almost ruthless with enemies (for instance, see Deuteronomy 7,20) meant that they were under obligations to their kinsmen to love, and should hate the outsiders (who were all pretty much enemies, since they were in enmity with the God of Israel).
Funnily enough, Christopher Hitchens is in agreement with the traditional understanding of to whom the love should concern: he found it dangerous that anyone would be told to love their enemies, since they must be dealt with. This is, in fact, true - to a degree: at a national law level, it is important that the state be allowed to wage a "just war" or whatever need be. It is important, for instance, that Great Britain not turn the other cheek and love the Third Reich during WWII. Hence, for the United Kingdom, "love your neighbour and hate your enemies" should be the law.
But I say to you, Love your enemies and pray for those who persecute you...(v. 44)
Individuals, however, are not nations. With this in mind, Jesus says that we as persons and the Church as a whole (since Matthew often speaks to the disciples as a place-holder for the future Church, for instance see a comment made here) must love even our enemies.
We will be eternally confused if we persist in our modern day notions of love with this passage. How are we meant to feel nice things about our enemies? Such people would not be our enemies if we wanted to hug them and hold their hands along the shore! It is prudent, therefore, to redefine our notions of love in a Christian context to the underlying Greek agape. Perhaps even using the Latin-derived charity would also do well, though even charity has connotations of mere niceness. At the end of the matter, we must understand that the call to love is self-giving, even to those who we want to give nothing at all: our enemies.
What about prayer? I think this is added to emphasize the point, and accentuate it. This love is not a matter of being polite to one's enemies, or a respect for their human dignity out of common decency. Jesus definition of love may as well be this: love is actively seeking the good of the object of that love. What does one do for those whose good one seeks? One prays for them. One also does many other things, but it takes an odd strain of love (the one we are asked to have) to pray for the one by whom one is persecuted. The (wordly) desire tends to be one of "I shall be nice to them if you want, but I do not desire to have to live with them for all eternity in heaven."
that you may be sons of your Father who is in heaven; for he makes his
sun rise on the evil and on the good, and sends rain on the just and on
the unjust." (v. 45)
What does loving have to do with being a son of the Father? I suspect the link is a culturally bound one where "like father, like son" was a lot closer. I think, and I may well be wrong, that what Jesus is saying is "so that you may be like your Father in heaven," but with the much stronger usage of the very powerful similarity between parent and child. This interpretation seems to be confirmed by the next clause in which God is said to bring rain and sunshine on all without partiality, indicating God's love for both the just and unjust.
Note: I'll leave for another time the justice in being impartial between the just and unjust.
For if you love those who love you, what reward have you? Do not even the tax collectors do the same? And if you salute only your brethren, what more are you doing than others? Do not even the Gentiles do the same? (vv. 46-47)
Jesus points out that loving the people it is easy to love, or the ones we have those feelings for, is not actually something of moral worth. What takes real mettle is doing it when one does not really want to anyway. The language is a little different to that, though: "what reward have you?" Well, what reward would we have the other way? It seems much more rewarding to love those who love us back!
We will see in the next section, chapter six, that there is more than one kind of reward, more than one kind of treasure - and we should be aiming to be rewarded from our heavenly Father, and accrue treasures in heaven.
You, therefore, must be perfect, as your heavenly Father is perfect. (v. 48)
There is two levels of meaning here; first, as an end to this sixth antithesis, and second as an end to all six antitheses.
As an ending to this subsection, we ought to note the Semitic use of the term "perfect." Jesus does not ask us to be omnipotent, omniscient and omni-benevolent, nor is he just asking for us to be omni-benevolent in the sense of lacking imperfections. This is, in a way, a standard we should aim for, but here perfect means "full" - like how "brought to perfection" is synonymous with "brought to completion", even though the first kind is a somewhat archaic use of the term. Our love should be complete, full - in just a word, perfect.
As an ending to the whole passage of the antitheses, this deepening of the law to its fullness is what Jesus began saying he would do (I have come not to abolish, but to fulfil), so that anybody who follows this deeper law to the very letter is indeed perfect, at least in moral terms.
It therefore sets the tone for the moral life - who can do this? Of course, the Christian answer has always been: Jesus alone.