In Luke 6:27-36 Jesus connects those who are rich, full and content with the status quo (Luke 6:24-26) with both the enemies of the Gospel and the enemies of the poor (the hungry, those who weep). Jesus claims that the evidence shows the rich (as a rule) hate the poor and the hungry, separating themselves from their company. Moreover (as a rule), they will defame those who embrace the hope given the poor by Christ, sending them away as though they were guilty of the world’s ills (cf. Luke 6:22). In recent history the America rich and powerful did this with the Blacks and even the Jews. Most recently they do it with illegal immigrants Nevertheless, Jesus’ disciples are called upon to love their enemies (Luke 6:27a), but what does that mean, and what does loving one’s enemy look like in real life?
First of all, it seems, if we have the intention of loving our enemies, we need to know who they are. They cannot always be identified with the obvious enemies who may seek our life or want to seize our goods for themselves. They often work in secret in an effort to destroy the fruitfulness of our labor (Matthew 13:24-25). Imagine working successfully to raise the minimum wage only to find businesses raising their prices, causing the cost of living to go up, perhaps even to the point that recent wage increases buy less than what the smaller wage bought a short while ago.
Imagine, as well, how those, who are rich in themselves, don’t want believers in Jesus to be successful in what we do. They will often distort the truth we say or the truth about the church and God (Acts 13:10). Although they may not know us personally (or we them), they count believers as their enemies (Galatians 4:16). They count themselves enemies of the cross of Christ and serve their own private interests by moving and shaking more and more people, seeking to dignify their dishonest goals (Philippians 3:18-19), calling good evil and evil good (Isaiah 5:20; Proverbs 17:15). Our enemies are not simply those among us who are disobedient to Christ (2Thessalonians 3:14-15). The disobedient may merely lack faith enough to do with is right. Rather, our enemies are those who seek to further the goals of this corrupt world. They use their resources to empower a worldview against God (James 4:4). These are the people Jesus tells us to love. They are our enemies, but we must not behave as an enemy toward them.
Jesus tells his disciples to behave honestly toward the very ones who detest them, even to the point of aiding them whenever possible. That is, to lend a helping hand in personal pursuits, but not when those pursuits go against the Gospel (Luke 6:27). We are to speak well of people who choose to vilify us and pray for the very ones who slander us (Luke 6:28).
Matthew 5:39 puts the context of Luke 6:29-30 into the realm of doing evil. Furthermore, Exodus 22:26 puts that context into the realm of a debt one owes to others (e.g. employers, promises made, public or private loans etc). Contrary to how Jesus tells his disciples to act toward their enemy when he is in need (Luke 6:27-28), if we are indebted to an enemy who insults us, we shouldn’t resist (Matthew 5:39). Instead, we should give place for repeated wrongdoing without rebuke (Luke 6:29). Moreover, if our enemy uses the law against us for his own advantage (cf. Exodus 22:26), we are to allow it. Not only so, but if he takes advantage of us more than the law allows, were are not to complain but permit that as well (Luke 6:30).
The Golden Rule in its positive form (as much as I can tell) is unique to Jesus. This is not so in its negative form, however. Barclay tells us in his commentary:
“That rule exists in many writers of many creeds in its negative form. Hillel, one of the great Jewish Rabbis, (claimed) ‘What is hateful to you, do not to another. That is the whole law and all else is explanation.’ Philo, the great Jew of Alexandria, said, ‘What you hate to suffer, do not do to anyone else.’ Isocrates, the Greek orator, said. ‘What things make you angry when you suffer them at the hands of others, do not you do to other people.’ The Stoics had as one of their basic rules, ‘What you do not wish to be done to yourself, do not you do to any other.’ When Confucius was asked, ‘Is there one word which may serve as a rule of practice for all one’s life?’ he answered, ‘Is not Reciprocity such a word? What you do not want done to yourself, do not do to others.’”
The difference between the two (i.e. positive and negative) is that, in its negative form, no further obligation is placed upon the righteous than not doing evil to another. Only in its positive form are we confronted with an obligation toward our brother (or enemy) to actually do good things for him. The positive form of the Golden Rule fills up the vacuum left by simply refraining from hurting someone else.
 Luke 6:29 isn’t speaking of someone who is seeking to kill us or to physically harm us. Notice that it is the right cheek that is struck. The Bible assumes men are right handed. If otherwise it brings this to our attention (cf. Judges 3:15; 20:16). In order to strike a man on the right cheek with one’s right hand, it must be with the back of one’s hand, showing this is intended to represent an insult.
 William Barclay: The Gospel of Luke; Revised Edition; The Westminster Press, Philadelphia; (1975), p.52.