Romans 3

As one reads the first two chapters and the beginning of the third chapter of Romans, it becomes very clear the importance of righteousness and obedience to the commandments of God. Paul makes it clear that this is not a light matter. Even some of the Roman converts were trying to justify sin and wickedness the demonstrate the righteousness of God. Paul strongly denounces such doctrine.

After establishing the will and conditions of the Lord of repentance and striving for righteousness, Paul acknowledges of he and his brethren, as ancient prophets so testified -

"...are we better than they? No, in no wise: for we have before proved both Jews and Gentiles, that they are all under sin;
10 As it is written, There is none righteous, no, not one..." (New Testament | Romans 3:9 - 10)

Suggesting that all are in need of repentance and the atonement of Jesus Christ. Is it any wonder he now teaches this true doctrine -

"Therefore by the deeds of the law there shall no flesh be justified in his sight..." (New Testament | Romans 3:20)

In this case, I believe he is speaking directly to the Jewish converts in their belief of the Mosaic law. He continues -

"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..." (New Testament | Romans 3:23 - 24)

Therefore, making it clear -

"Where is boasting then? It is excluded. By what law? of works? Nay: but by the law of faith." (New Testament | Romans 3:27)

Obedience to His commandments builds and demonstrates faith in Him. Paul explains this saying -

"Seeing it is one God, which shall justify the circumcision by faith, and uncircumcision through faith.
31 Do we then make void the law through faith? God forbid: yea, we establish the law." (New Testament | Romans 3:30 - 31)

In this case, he is suggesting to his Jewish converts, that the obedience to the Mosaic law does not and cannot in itsef bring salvation or justification. I believe he is not saying herein that the Savior came to destroy the law of Moses but to fulfill it. In other words, continual obedience to the law would help the Jewish converts remember to be obedient to the commanments and demonstrate faith in Him.

Those Christians that believe that all they have to do is accept Jesus Christ as their Savior, and all wickedness there after doesn't matter. If they believe that, they have not read the words of Paul to the Romans.

Nephi summarized this doctrine in these few words -

"For we labor diligently to write, to persuade our children, and also our brethren, to believe in Christ, and to be reconciled to God; for we know that it is by grace that we are saved, after all we can do." (Book of Mormon | 2 Nephi 25:23)

Why else would the Savior teach -

"If ye love me, keep my commandments." (New Testament | John 14:15)