Like this lawyer, he also thought that he could earn eternal life by doing some good thing. Jesus answers this lawyer in the same manner as He did the rich young ruler and that is by pointing them back to the law. By why did He do this?
According to one set, especially prominent in the Sermon on the Mount (Matthew 5–7), Jesus admonished his followers to observe the law unwaveringly (Matthew 5:17–48). According to another set, he did not adhere strictly to the law himself and even transgressed current opinions about some aspects of it, especially the Sabbath (e.g., Mark 3:1–5).
The Bible does not say anything about lawyers as we know them today. Israel was under the legal jurisdiction of Rome during Jesus’ time, so when the Bible mentions “teachers of the law” ( Luke 5:17) or “lawyers” ( Luke 14:3, ESV ), it is referring to the religious leaders who were experts in the Mosaic Law.
It is possible, Scot McKnight suggest, that Jesus has been accused of breaking the Law or teaching things which nullified the Law. There are several examples of the Pharisees questioning Jesus about certain practices such as eating with sinners (Matt 9:1-11), fasting (Matt 9:14), and Sabbath (Matt 12:1-13).
But Jesus did not respond as expected. He did not congratulate the lawyer as a man of good standing. To the contrary, he buckled the lawyer's knees and threw him into a ditch. He did so by telling a story, a parable.
Perhaps, that's the reason why he asked “who is my neighbor”? Perhaps, he was expecting Jesus to say: “your fellow Jews”, “your relatives” or “your friends”, in which case he can now say that he did that and thus save face. But Jesus was not finished with him. Jesus wanted to teach this lawyer a very important lesson.
In Matthew 5:17-18, Jesus says, "Do not think that I have come to abolish the law or the prophets; I have not come to abolish them but to fulfill them.
When asked which commandment is greatest, he responds (in Matthew 22:37): “Thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy mind…the second is like unto it, Thou shalt love thy neighbor as thyself. On these two commandments hang all the law and the prophets.”
And the lawyer replied: "He that shewed mercy on him." Then Jesus delivered His final instruction to the lawyer — and to all who have read the parable of the good Samaritan: "Go, and do thou likewise" (see Luke 10:25–37).
When Jesus asks which of these three – the priest, the Levite, or the Samaritan – acted as a neighbor to the robbed man, the lawyer answers “The one who showed him mercy.” As Jesus often does, he turns the question of “who is my neighbor?” on its head and instead answers “who might be a neighbor to me?”
In Matthew 22:36–40, a Pharisee lawyer asked Jesus "which is the great commandment in the Law?" Jesus responded, "You shall love the Lord your God with all your heart and with all your soul and with all your mind. This is the great and first commandment.
The World English Bible translates the passage as: "Don't think that I came to destroy the law or the. prophets. I didn't come to destroy, but to fulfill."
Jesus was clearly teaching obedience to the Roman laws and also to obey God's laws. The laws Jesus broke were the ones created by the religious leaders, hence religious laws dealing with Hebrew worship and doctrine, and had nothing to do with the civil laws of the land required by Rome.
The two most important things Jesus asked us to do was (1) love God and (2) love people.
Do not be anxious about tomorrow, for tomorrow will be anxious for itself. Let the day's own trouble be sufficient for the day. I am the Way, the Truth, and the Life. No one comes to the Father except through me.
Though times and customs changed, God's law served as a bedrock of guiding ideals to help the people of God (both then and now) live in such a way as to love God and love neighbor.