You think Jesus did not differentiate between "Hate your enemy" and the other examples of their accustomed teaching which He listed? Nothing could be more conspicuously incorrect! The instruction to hate one's enemies was the only example of the seven that Jesus both refuted and contradicted, because, in fact, it was not part of the mosaic legislation, as were the other six.Jesus doesn’t differentiate between the command to hate your enemy and the other commands that “were said to the men of old.” They are all lumped together. Why didn’t Jesus say of the other commands to which He referred in the books of Moses “The Father said to you …, but I say to you …”? Had He done so, it would certainly have appeared that Jesus was teaching differently from the Father. But He wasn’t!
Concerning the first six examples given (Do not murder; Do not commit adultery; Give a bill of divorce, if you divorce your wife; Do not swear falsely; An eye for an eye, a tooth for a tooth; Love your neighbor), Jesus made no objection, raised no contradiction, and, in fact, offered no commentary that could not already be found elsewhere (stated or implied) in the Old Testament.
Of the first example, He did not revoke or disagree with the command against murder, but simply added that one also must not be unjustly angry. The Old Testament had plenty to say against inappropriate anger (Prov.14:17; 22:24; 29:22/ Eccl.7:9/ Jonah 4:4). This was not a new revelation from Jesus, just a new connection to the sixth commandment.
Of the second example, He did not revoke the command against adultery, but He added that one also must not lust after a woman. Such lust was already condemned in the Old Testament (Ex.20:17/ Job 31:1/ Jer.5:8). Nothing new here either.
Of the third example, He expressed no disagreement with the custom of giving a writ of divorce when divorcing. He merely clarified that there is only one ground for divorce that God will recognize. In another place (Matt.19:1-9), He based this very same teaching upon the Old Testament record of the first marriage (Genesis 1 and 2), which suggests that they should have been able to figure this out (without Jesus) from what Moses had already written in the Torah. In fact, in that place, He prefaced His statement about no ground for divorce other than fornication with the question, "Have you not read [Genesis 2:24]?" Clearly, He was not claiming to be presenting a new idea, absent from the Torah.
Of the fourth example, He said that one ought to get along without any oaths at all (though He did not say, as if to contradict Moses, that one is now free to break his oaths). The Old Testament never commanded people to make oaths (except in the case of one who had lost property entrusted to him), so Jesus' telling His disciples to live without oaths can hardly be said to contradict any command of Moses on the subject. Ecclesiastes 5 talks about oaths, and also makes it clear that it is often better to make no oaths. Jesus gave no new ethic here, either.
Of the fifth example, Jesus said that one ought not to press his legal rights to retaliation (though He gave no indication that the courts, when prosecuting a violent crime, should adopt some code of punishment different from that of Moses). "Turning the other cheek" was always an option in the Old Testament (David did so with both Saul and Shimei), and presents no violation of the civil code of criminal punishments. In other words, the law telling the courts that the proper punishment for one who has taken another man's eye was that the assailant should lose an eye of his own was never intended to deprive the victim of the right not to press charges. This is the option that Jesus encouraged His disciples to take.
Of the sixth example, He agreed that one ought to love his neighbor (just as Moses said), but clarified that one's enemy is also a neighbor and should be loved as well. Teaching to the contrary by the rabbis had been misleading—and even contrary to the mosaic legislation! Loving enemies has many precedents in the Old Testament (e.g. Exodus 23:4-5/ Prov.25:21-22/ 1 Sam.24:10-11/ 2 Sam.18:5/ 2 Kings 6:21-23). There was nothing new or novel (just something ignored by the rabbis) in Jesus' command to love enemies. The Christian obligation to love is "no new commandment...but an old commandment which you have had from the beginning" (1 John 2:7).
In no point in the Sermon on the Mount did Jesus abrogate or show any dissatisfaction with the laws given by Moses. However, He sharply renounced the command to hate one's enemy, for the simple reason that, unlike the other examples given, it was a man-made, and wrong-headed, commandment.
It is true that Jesus said, "You have heard it said by (or to) those of old times..." rather than, "You have heard the Father say..." But this is entirely irrelevant to proving your point, since He was simply referring to a variety of things they had often heard rabbis say in the synagogues. It goes without saying that very much, if not most, of the rules taught by the rabbis would either be the laws of God, which the rabbis were obliged to teach, or applications of those laws that were unobjectionable.
This assumption lies behind Jesus' instruction to His disciples, elsewhere, that they ought to observe "everything [the rabbis, speaking from Moses' seat in the synagogue] bid you to observe and do" (Matt.23:2-3). Obviously, most (but not all) of the things taught from Moses' seat would be derived from and consistent with the divine law. In Jesus representations of what the disciples had often heard (but never adequately understood) in the synagogues, it is predictable that most of the content would have been the commandments of God, and this is what we find to be the case in Jesus' selection of points to elucidate.
When Jesus said, "You have heard...but I say to you..." the second part was not to be taken as a contradiction, an abolition or renunciation of the first, but rather as a way of saying, "Your teachers have told you this much... but I say they did not go nearly far enough! The Law implies much more than the rabbis have understood or taught! I will now fill-in what they neglected to tell you..." It is astonishing that one could think that Jesus, in Matthew 5:21-48, would commence to dismantle the law of Moses, immediately after He had declared that He had not come to do any such thing (vv.17-20).
Your suggestion that "the commandment of God," in Mark 7, did not include the command to kill disobedient children is a stretch in the extreme! Jesus' whole point was to contrast the "word of God" from the "traditions" concocted by man. In doing so, He places two commandments (both of which "Moses said") in juxtaposition against the traditional practices of the Pharisees. He clearly intended to say that these things that Moses had said were "the commandments of God" which the Pharisees were nullifying by their traditions. To suggest that the first mentioned law of Moses was presented as authoritative, but the second was not raises insuperable difficulties. In making His point, why did Jesus include a law which (you say) was not a law of God, alongside one that clearly was a law of God, and then say that the Pharisees had violated them by their traditions—if, in fact, even one of the two was itself such a tradition?
Paidion, you are a clever man, but your intelligence is not put to good use when you employ it in dodging the clear teaching of Jesus, fabricating fantastic subterfuges of extremely unlikely interpretations, simply to avoid admitting that your doctrine is faulty. I know and regret that this comment may hurt your feelings, and I never do so lightly or happily, but I can see your arguments in no other light—they are so far-fetched! Sometimes it is better just to say, "You know, I may have been wrong about that."