"And behold, it is written, an eye for an eye, and a tooth for a tooth; But I say unto you, that ye shall not resist evil, but whosoever shall smite thee on thy right cheek, turn to him the other also;"
This is reforming the law of retaliation or lex talionis. When first adopted, the law of retaliation was designed to limit retribution. It was merciful in the context of the time. It prevented taking a life for an eye. The scope of the injury suffered put a limit on the scope of the retaliation permitted. I taught a class on this ancient law in the BYU Education Week some years ago. It is too much to cover in this post in order to fully understand the ramifications of this law.
The popular understanding of that law is quite a distortion. The injury permitted was not actually exacted under the law. "An eye for an eye" meant that the victim was entitled to take the eye of the one causing the injury. In practice the eye was not taken. The value of the eye was agreed upon between victim and perpetrator. They sealed the agreement before two witnesses in the gate of the city. Then the debtor was obligated to pay the agreed sum (called "satisfaction"). If he defaulted the elders could take the eye as penalty for the default in payment, which stood as collateral for the debt.
Payment of "satisfaction" was permitted and given for offenses under the lex talionis except in the case of a limited class of offenses, including murder. (Numbers 35: 31-32.) In such cases it was considered too dangerous to allow satisfaction, and therefore the penalty needed to be carried out.
Here, Christ is replacing that entire body of law by substituting forgiveness and mercy for justice and recompense. The victim is being urged to seek nothing in return for his injury. Instead, the victim is to bear the injury and allow evil against themselves without retaliation for the offense.
This may seem odd, even wrong. However, there is an example of this in the Book of Mormon. Although many lives were lost in the process, it resulted in the salvation of many souls. The Anti-Lehi-Nephites were unwilling to take up arms to defend themselves, instead allowing their enemies to slay them. The result broke the hearts of those who were killing them, and many were converted by this example. (See Alma 24: 19-27.) But the people of God were joined by more than the number who were slain.
The book by C. Terry Warner titled The Bonds That Make Us Free: Healing Our Relationships, Coming to Ourselves
explains how the actions of those who forgive are able to break the hearts of those who are forgiven. There is not merely freedom in forgiving others, there is power in it as well. Terry Warner's book is an examination of the principles of sin and forgiveness, and worth reading if you have not done so before. We gain power by what things we suffer for the Lord's sake. Christ who loved the most, sacrificed the most. Those two things are linked together.
This teaching was not only given by Christ, but it was lived by Him also. In this statement, as in no other, He is defining who He is and revealing what His conduct invariably will be. This is the Lord's standard. This is the Lord's manner. The choice of turning the other cheek is taken from the Messianic standard described by Isaiah. (Isa. 50: 6; also 53: 5.) We can also heal others by the things we willingly suffer. We can endure and forgive. As we do righteousness increases on the earth.
Saint Francis Assisi believed this, practiced it. In an age of darkness and apostasy, the Lord spoke with St. Francis, and sent angels to minister to him. He is appropriately referred to as a Saint. He lived the Sermon on the Mount. It is perhaps St. Francis, who above all others, proves a mortal may walk in the Lord's steps. Christ did it first and more completely than would any other. But St. Francis surely followed.
I have little doubt that the Lord's teachings are impractical in this world. But, then again, we are not called to live for this world, are we? The reason Zion always flees from this world is precisely because the Lord will not permit the world to overwhelm those who would surely be overthrown if not for His grace and protection. He will fight their battles to spare those in Zion from the necessity of becoming warlike. (D&C 105: 14.)
I am amused by the martial inclinations of the Latter-day Saints. When the lamb and lion lie down together I suppose many of the Latter-day Saints expect to be able to hunt them both.