You remain confused about the administration that is in place during the events and instructions described in Matthew thru John.
1 - That economy or administraton was the Law of Moses.
Notice how early in Matthew this is...
Matthew 5:17 Think not that I am come to destroy the law, or the prophets: I am not come to destroy, but to fulfil. 5:18 For verily I say unto you, Till heaven and earth pass, one jot or one tittle shall in no wise pass from the law, till all be fulfilled. 5:19 Whosoever therefore shall break one of these least commandments, and shall teach men so, he shall be called the least in the kingdom of heaven: but whosoever shall do and teach them, the same shall be called great in the kingdom of heaven. 5:20 For I say unto you, That except your righteousness shall exceed the righteousness of the scribes and Pharisees, ye shall in no case enter into the kingdom of heaven.
And notice how late in Matthew He is still emphasizing living under the Law of Moses...
Matthew 23:1 Then spake Jesus to the multitude, and to his disciples, 23:2 Saying, The scribes and the Pharisees sit in Moses' seat: 23:3 All therefore whatsoever they bid you observe, that observe and do; but do not ye after their works: for they say, and do not.
2 - What did the Lord later reveal to and thru the Apostle of the Gentiles about what God had actually been doing thru those commands under the Law in Matthew thru John?
Romans 3:19 Now we know that what things soever the law saith, it saith to them who are under the law: that every mouth may be stopped, and all the world may become guilty before God. 3:20 Therefore by the deeds of the law there shall no flesh be justified in his sight: for by the law is the knowledge of sin.
3-What else did the Lord also reveal later to and thru said Apostle of the Gentiles?
3:21 But now the righteousness of God without the law is manifested, being witnessed by the law and the prophets; 3:22 Even the righteousness of God which is by faith of Jesus Christ unto all and upon all them that believe: for there is no difference: 3:23 For all have sinned, and come short of the glory of God; 3:24 Being justified freely by his grace through the redemption that is in Christ Jesus: 3:25 Whom God hath set forth to be a propitiation through faith in his blood, to declare his righteousness for the remission of sins that are past, through the forbearance of God; 3:26 To declare, I say, at this time his righteousness: that he might be just, and the justifier of him which believeth in Jesus. 3:27 Where is boasting then? It is excluded. By what law? of works? Nay: but by the law of faith. 3:28 Therefore we conclude that a man is justified by faith without the deeds of the law.
As for sin on this side of all that?
Romans 5:19 For as by one man's disobedience many were made sinners, so by the obedience of one shall many be made righteous. 5:20 Moreover the law entered, that the offence might abound. But where sin abounded, grace did much more abound: 5:21 That as sin hath reigned unto death, even so might grace reign through righteousness unto eternal life by Jesus Christ our Lord.
Romans 6:1 What shall we say then? Shall we continue in sin, that grace may abound? 6:2 God forbid. How shall we, that are dead to sin, live any longer therein?
Romans 6:7 For he that is dead is freed from sin.
Romans 6:12 Let not sin therefore reign in your mortal body, that ye should obey it in the lusts thereof. 6:13 Neither yield ye your members as instruments of unrighteousness unto sin: but yield yourselves unto God, as those that are alive from the dead, and your members as instruments of righteousness unto God. 6:14 For sin shall not have dominion over you: for ye are not under the law, but under grace.
Romans 6:15 What then? shall we sin, because we are not under the law, but under grace? God forbid.
Romans 6:16 Know ye not, that to whom ye yield yourselves servants to obey, his servants ye are to whom ye obey; whether of sin unto death, or of obedience unto righteousness?
Romans 6:17 But God be thanked, that ye were the servants of sin, but ye have obeyed from the heart that form of doctrine which was delivered you.
What form of doctrine was that? See Romans 3:21-28 quoted hereinabove, in point #3.
Result?
Romans 6:18 Being then made free from sin, ye became the servants of righteousness.
Romans 6:19 I speak after the manner of men because of the infirmity of your flesh: for as ye have yielded your members servants to uncleanness and to iniquity unto iniquity; even so now yield your members servants to righteousness unto holiness.
