Do not be surprised by the question, it is not an insolent question; the question is legitimate and is based on the context of the Mosaic Law of the religious thought of those who listened to the doctrine of Jesus; why carry the burden for two miles, if the Law authorizes us to carry it for one, when the case merits it?
The Jews, accustomed to doing all things based on some precept of the Law and the tradition of the elders, did not see Jesus’ instruction as an attack on their doctrinal foundation; Jesus’ instruction was not a new commandment, they knew perfectly well what Jesus was referring to, what was new about the instruction was that Jesus extended the permitted limits of how far they were obliged to do things. Why?
The reader can verify from the text of the account that Jesus’ instruction was established in teaching on the basis of, ‘eye for an eye, tooth for a tooth‘, a statute of the Mosaic Law, better known as the law of restitution for the damage done to second and third persons. The precept of the law established that the restitution had to be of the same magnitude as the damage done. In the book of Leviticus we read the statement of this law:
17 And he that killeth any man shall surely be put to death. 18 And he that killeth a beast shall make it good; beast for beast. 19 And if a man cause a blemish in his neighbour; as he hath done, so shall it be done to him; 20 breach for breach, eye for eye, tooth for tooth: as he hath caused a blemish in a man, so shall it be done to him again. 21 And he that killeth a beast, he shall restore it: and he that killeth a man, he shall be put to death. 22 Ye shall have one manner of law, as well for the stranger, as for one of your own country: for I am the Lord your God.Leviticus 24:17-22
In that sense, eye for eye, tooth for tooth, means that any damage in which each one incurs will be amended in the same way, and in the same magnitude, of the damage produced; the law is clear in specifying that according to the injury that will have done to another, such will be done to him, and not for questions of revenge, but to mean that all damage has to be amended without leaving any consequence without rectifying. The law does not contemplate the possibility of ‘revenge’, it is not a law of revenge, on the contrary, it is a didactic law that established respect and that recognized the ‘right’ that everyone has to have his property respected.
The law was enacted not only as a tool to punish the conduct of those who inflicted harm on others; the law had the dual purpose of the people learning to set limits on their personal actions in relation to those closest to them, on the one hand; but, primarily, to bring the people to the understanding of the need to restitute those who fall into loss of property and disrepute of dignity; a purpose quite similar to that established with respect to the celebration of the Jubilee years, in which the restoration of the property and liberties of those who had fallen into slavery because of unpayable debts was enacted.
8 And thou shalt number seven sabbaths of years unto thee, seven times seven years; and the space of the seven sabbaths of years shall be unto thee forty and nine years. 9 Then shalt thou cause the trumpet of the jubile to sound on the tenth day of the seventh month, in the day of atonement shall ye make the trumpet sound throughout all your land. 10 And ye shall hallow the fiftieth year, and proclaim liberty throughout all the land unto all the inhabitants thereof: it shall be a jubile unto you; and ye shall return every man unto his possession, and ye shall return every man unto his family.Leviticus 25:8-10
When Jesus quotes the law, eye for an eye and tooth for tooth, and teaches about the virtue of carrying the burden for two miles, He is not establishing that the previous law ceased to have validity and meaning, He does it rather to establish a more excellent way in the path of justification by faith in God. Note in the account that just before establishing the teaching of carrying the burden for two miles, Jesus emphasized: Do not resist evil, meaning by this, do not seek to impose your right against the one who harms you. What is the more excellent way, in what does it consist? How does carrying the burden for two miles make me more righteous?
To carry the burden for the first mile when I do not want to do it, that is, when I am forced to do it, according to eye for eye and tooth for tooth, represents the ‘damage’ caused on my person; my right is represented in the first mile, I am in my right that the one who forces me to carry the burden should also pay in the same way, that is, that he also carries the burden for a mile. But Jesus said, do not seek to enforce your right against the one who harms you, which means, give up your right of restitution. Why give up my right?
In an alternate teaching Jesus taught that the damage that man suffers will not go unpunished, that his damage will be restored, and He taught that it is better to be restored by God Himself: thy Father which seeth in secret himself shall reward thee openly (6:4,6,18). From this teaching arises the following statute of faith:
23 Therefore is the kingdom of heaven likened unto a certain king, which would take account of his servants. 24 And when he had begun to reckon, one was brought unto him, which owed him ten thousand talents. 25 But forasmuch as he had not to pay, his lord commanded him to be sold, and his wife, and children, and all that he had, and payment to be made. 26 The servant therefore fell down, and worshipped him, saying, Lord, have patience with me, and I will pay thee all. 27 Then the lord of that servant was moved with compassion, and loosed him, and forgave him the debt… 32 Then his lord, after that he had called him, said unto him, O thou wicked servant, I forgave thee all that debt, because thou desiredst me: 33 shouldest not thou also have had compassion on thy fellow servant, even as I had pity on thee? 34 And his lord was wroth, and delivered him to the tormentors, till he should pay all that was due unto him. 35 So likewise shall my heavenly Father do also unto you, if ye from your hearts forgive not everyone his brother their trespasses.Matthew 18:23-35
What does the second mile mean? The second mile represents according to, eye for an eye and tooth for a tooth, the mile that is due ‘to pay’ to the one who harmed you for having forced you to carry the burden for a mile; Jesus said: do not demand that he carry the burden for the mile that is due to him, do it for him. The second mile represents the evidence that you do not claim your right of restitution, and that you have decided to ‘forgive’ your offender.
Scripture quotations are taken from the Authorized King James Version, 1909 (AKJV).
Pastor Pedro Montoya
 Philippians 3:7-8: But what things were gain to me, those I counted loss for Christ. 8 Yea doubtless, and I count all things but loss for the excellency of the knowledge of Christ Jesus my Lord: for whom I have suffered the loss of all things, and do count them but dung, that I may win Christ,
 Matthew 18:21-22: 21 Then came Peter to him, and said, Lord, how oft shall my brother sin against me, and I forgive him? till seven times? 22 Jesus saith unto him, I say not unto thee, Until seven times: but, Until seventy times seven.