By remaining in faith alone through Christ alone, we remain obedient His Plan, rather than obedient to only His Law.
Consider Romans 3:22, with close attention on the prepositional phrasing:
Rom 3:19-28
(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.
(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.
(21) But now the righteousness of God without the law is manifested, being witnessed by the law and the prophets;
(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:
(23) For all have sinned, and come short of the glory of God;
(24) Being justified freely by his grace through the redemption that is in Christ Jesus:
(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;
(26) To declare, I say, at this time his righteousness: that he might be just, and the justifier of him which believeth in Jesus.
(27) Where is boasting then? It is excluded. By what law? of works? Nay: but by the law of faith.
(28) Therefore we conclude that a man is justified by faith without the deeds of the law.
Romans 2:
12] For as many as have sinned without law shall also perish without law: and as many as have sinned in the law shall be judged by the law;
[13] (For not the hearers of the law are just before God, but the doers of the law shall be justified.
[14] For when the Gentiles, which have not the law, do by nature the things contained in the law, these, having not the law, are a law unto themselves:
[15] Which shew the work of the law written in their hearts, their conscience also bearing witness, and their thoughts the mean while accusing or else excusing one another;)
A read through the epistle of James, which like Romans, was also written to the out of covenant House of Israel, might also be in order