I want to be respectful. If I come across as condescending at any point here, that's not my intention; please have mercy.
Hmmm, looks like James 2:17. When I consider the greater context, it appears James is describing faith in action; a supernatural phenomenon that occurs when one is 'walking in the spirit' or the Holy Spirit is working through a believer. I don't see any mention of atoning benefits or adding to what Jesus did on Calvary.
Let's explore an even greater context. Remember in John 8 where people were judging a women in adultery and Jesus told the people that whoever was without sin may cast the first stone? Then Jesus said, "Woman, where are those your accusers? has no man condemned you?" She said, "No Lord." And Jesus said, "then neither do I condemn you: go, and sin no more." He did that because he knew he would bear her sins on the cross. By extending undeserved, unmerited Grace to her, He empowered her to "go and sin no more".
For Christ's love compels us, because we are convinced that one died for all, and therefore all died. (2 Corinthians 5:14)
Romans explains when one has a revelation of God's grace and unmerited favor, sin no longer has dominion over them.
For sin will have no dominion over you, since you are not under law but under grace. (Romans 6:14)
There are no discrepancies here; we are saved through faith, not works, lest any man should boast. Overwhelmingly the Bible tells us that we are saved through faith alone apart from works.
"For by grace are ye saved through faith; and that not of yourselves it is the gift of God Not of works, lest any man should boast" (Eph. 2:8-9).
"But to him that worketh not, but believeth on him that justifieth the ungodly, his faith is counted for righteousness" (Rom. 4:5).
"Not by works of righteousness which we have done, but according to his mercy he saved us, by the washing of regeneration, and renewing of the Holy Ghost; Which he shed on us abundantly through Jesus Christ our Saviour; That being justified by his grace, we should be made heirs according to the hope of eternal life." (Titus 3:5-7)
Romans 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."
Galatians 2:16 "Knowing that a man is not justified by the works of the law, but by the faith of Jesus Christ, even we have believed in Jesus Christ, that we might be justified by the faith of Christ, and not by the works of the law for by the works of the law shall no flesh be justified."
John 3:15-16, 36 "That whosoever believeth in him should not perish, but have eternal life. For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life. He that believeth on the Son hath everlasting life and he that believeth not the Son shall not see life; but the wrath of God abideth on him."