What was the was the purpose of the transfiguration on the Mountain in Matthew 17? And What did Jesus Mean in Matthew 5:17?

Matthew 17:1-13

In Matthew 17 when Jesus was transfigured on the mountain several very important things happened which we must take note of.

1) He took with Him Peter, James and John, (they were to serve as witnesses of what was about to take place).

2)Moses and Elijah appeared on the mountain. (Moses represents the law {the ten commandments which was given to him on Mount Sinai and the rest of the law which was given to him}. Elijah, being the most well known prophet, represents the prophets. Now to re-cap, now on the mountain where Jesus was transfigured we have the Law, Moses representing (The old covenant given on Mt. Sinai, the old Covenant was the Law), and then we have the Prophets, Elijah representing the Prophets. But who does Jesus represent in this picture? He represents the Son of God and the mediator of the New Covenant.

3)Now there is a voice that is heard from the cloud in verse 5 that says something very very important, the voice says "“This is my Son, whom I love; with him I am well pleased. Listen to him!”" That voice is God the Father, But why did He say what He did, especially why did He say "Listen to Him" that is, listen to Jesus Christ? Why didn't He say listen to Moses or listen to Elijah?

Well, here we have the voice of God the Father from heaven saying in the presence of not 1, not 2, but 3 witnesses, REMEMBER (by the mouth of two or three witnesses every word is established, Matthew 18:16), that we are to listen to Jesus Christ; and who does Jesus represent again in this scenario? The Son of God and the mediator of the New Covenant. So, what is happening here is the ushering in of the New Covenant, and the Old Covenant although it served a purpose of being our tutor to lead us to Christ. (Galatians 3:24), it is now being made obsolete, and growing old ready to vanish away, (Hebrews 8:13). Why? Because of it's weakness and unprofitableness, for the law made nothing perfect... Hebrews 7:18-19. So what happens now? Well, "there is a bringing in of a better hope, through which we draw near to God." But who is the mediator of that better hope which is the New Covenant? Jesus Christ, Hebrews 9:15.

Okay, back to the transfiguration. Who was on the Mountain again?Moses (Law), Elijah (Prophets,  and Jesus Christ. Again, who does Jesus represent in this very important event? As I just shared He is the mediator of this new Covenant. So what is happening here in Matthew 17? In short, God is letting us know we are now to listen to His Son Jesus Christ, who is greater than Moses and Elijah, we are to now live under the New Covenant and not the old. (For further study read the Book of Romans, Galatians and Hebrews especially).

Matthew 5:17

Another scripture many legalists and persons without understanding have misconceptions about is Matthew 5:17 when Jesus stated, "I did not come to destroy the law or the prophets but to fulfill them." Many take this to mean, "See, He didn't come to destroy it so it's still in effect." That misconception comes mostly because of erroneous teaching by the untaught and unstable who twist the scriptures (2 peter 3:16), and that understanding also comes from leaning on your own understanding. Many fail to see that in that scripture two options are presented. Below are the options along with the definitions of what these words mean:

Option (A): To Destroy

destroy (dɪˈstrɔɪ)
vb (mainly tr)
1. to ruin; spoil; render useless
2. to tear down or demolish; break up; raze
3. to put an end to; do away with; extinguish
4. to kill or annihilate
5. to crush, subdue, or defeat
6. (intr) to be destructive or cause destruction

Option (B:) To Fulfill
ful·fill also ful·fil (fl-fl)
tr.v. ful·filled, ful·fill·ing, ful·fills also ful·fils
1. To bring into actuality; effect: fulfilled their promises.
2. To carry out (an order, for example).
3. To measure up to; satisfy. See Synonyms at perform, satisfy.
4. To bring to an end; complete.
Adj. 1. fulfilled - completed to perfection
consummated - brought to completion; "a consummated transaction"

Now which option did Jesus choose? He Chose B. But the both of them have something very important in common, either way both bring whatever there may be to an end. When something is fulfilled it is carried out, it is brought to completion. If a prophecy has been fulfilled, what do you do, sit and wait for it to be fulfilled again? So, Jesus came and fulfilled (carried out) what was written of Him in the Law and the Prophets and in the Psalms, just as He said, "And, He said unto them, these are the words which I spoke unto you, while I was yet with you, that all things must be fulfilled, which were written in the law of Moses and in the prophets and in the psalms concerning me." Luke 24:44. A greater has come, but still many want to cling onto Moses (the Old Covenant, the Law).
All of this is only hard to understand when a person has gone dull of hearing. Hebrews 5:11.

The conclusion. Why did all of this have to happen? Because God loves us, so He made Jesus the propitiation (atonement) for our sins, through Him we are reconciled to God, through Him we have eternal life, 1 John 5:11-12. Eternal life does not come through the law, righteousness does not come through the law, but through faith in Jesus Christ, Romans 3:22. For those who still choose to remain under bondage by the law but say they have faith, they must know that it is written that the law is not of faith, Galatians 3:12, so either you have the law or you have faith, you can't have both, you can't be both free and in bondage. Also, the promise made by God to Abraham and his (Seed) does not come through the Law (The promises were spoken to Abraham and to his seed. Scripture does not say "and to seeds," meaning many people, but "and to your seed," meaning one person, who is Christ. Galatians 3:16), only through Jesus Christ can one obtain the promise. In fact Galatians 4 explains that to us by using Hagar and Sarah, both being symbolic representing both covenants, the Old and the New. Hagar (a bond woman/slave and mother of Ishmael) represented the law given to Moses on Mt. Sinai (which gave birth to bondage),Galatians 4:24; and Sarah ( a free woman and mother of Isaac) represented the New Covenant. All those who remain under the Law remain in bondage like Hagar and are not heirs to the promise. Why? Because "The Bond woman will not be heir with the son of the free woman." Galatians 4:30. But who are we who are under the New Covenant? We are children of the free woman, hence we are heirs. We are free because of Jesus Christ. It is important to understand all of this, because we do not want to fall from grace and be estranged from Christ (Galatians 5:4-6). The law of the New covenant is love, God's perfect and Holy love. We are repeatedly reminded in scripture that Love fulfills the Law. That once we Love God with all our heart, mind, soul and strength, and also love one another the way God loves us, we have fulfilled the law. But yet many choose to remain under the old covenant when a greater and better has come in Jesus Christ. I hope this has helped many to understand the purpose of the new Covenant and I hope this cleared up some misunderstandings about a few other scriptures.