Matthew 5:43, "Ye have heard that it hath been said, Thou shalt love thy neighbour, and hate thy enemy."As a bit of background, the use of love and hate in Semitic languages is different than it is in modern English. Ancient Semitic languages, like Hebrew, generally did not use comparative terms "I love my son more than my daughter." To say that in ancient Hebrew, you would say "I love my son. I hate my daughter." This is not to say that you hate your daughter or even that you love your son. You simply love one more than the other.
This passage, which is pretended by Matthew to be taken from some part of our Scriptures, originated partly in his own imagination. Scripture no where bids us to hate our enemy, but teaches us a totally different doctrine; for we find in Exodus 23:4, 5, "If thou meet thine enemy's ox or his ass going astray, thou shalt surely bring it back to him again. If thou seest the ass of him that hateth thee, lying under his burden, and wouldst forbear to help him, thou shalt surely help with him." See also Leviticus 19:17, 18, "Thou shalt not hate thy brother in thine heart: thou shalt rebuke thy neighbour and not suffer sin upon him. Thou shalt not avenge nor bear any grudge against the children of thy people, but thou shalt love thy neighbour as thyself. I am the Lord." Again, in the Book of Proverbs 24:17, "When thine enemy falleth do not rejoice, and when he stumbleth let not thine heart rejoice." And ibid 25:21, "If thine enemy be hungry, give him bread to eat, and if he be thirsty, give him water to drink."
Then Joab came into the house to the king and said, “You have today covered with shame the faces of all your servants, who have this day saved your life and the lives of your sons and your daughters and the lives of your wives and your concubines, because you love those who hate you and hate those who love you. For you have made it clear today that commanders and servants are nothing to you, for today I know that if Absalom were alive and all of us were dead today, then you would be pleased. (2 Samuel 19:6-7)This verse implies in some sense that you are to love those who love you and hate those who hate you. Remember that in the Semitic tongue, the love/hate comparison is not an absolute one. Joab may very well have been saying that you are to love your neighbors more than your enemies.
Jesus took this likely well-known slogan and turned it on its head. A. Lukyn Williams writes that this teaching about loving your neighbor and hating your enemies was a popular slogan, not a Scriptural prooftext. Tacitus confirms this in volume 5 of his histories, stating that the Jews had absolute trust for other Jews, but absolute emnity and hatred for all outsiders. From Williams:
For though love to enemies was taught in the Law (and Jesus does not say the contrary), and though it was taught by individual Jewish leaders before our Lord's time, or independently of Him about the same time, there is no reason to think that it was ever the popular theory or practice. So far from this, it may be pointed out that the precept "Love your enemies" is not the popular theory or practice even now, either among Jews or Christians. The religion of an ordinary man down to this twentieth century has always permitted hatred of a private enemy.