There are those who say that James supports faith plus works for salvation. That is not what the Holy Spirit through Paul teaches in that He says, "By grace are we saved through faith, not of ourselves, but it is the gift of God, not of works lest any should boast. He is quite clear, and because the Holy Spirit doesn't contradict Himself, He does not say any different through James.
While Paul says that salvation comes by grace through faith, James says that works demonstrate a person is already genuinely converted to Christ. This is because part of a genuine conversion, one must repent and forsake sinful behaviour and habit patterns. When a person demonstrates a transformed heart that hates sin and loves holiness, he is demonstrating true faith in Christ.
But what those who misinterpret James say, is that a person has to add good works to faith in order to be saved. But Paul says that is a person is to be saved through works, he has to do the works perfectly without a single fault from his youth onwards. So, if a person comes to Christ in his adulthood, after engaging in sinful practices, his faith alone in Christ erases those past sins. But if he is depending on good works, then those past sins are still on the books.
It is the same as a person who has raped three women and cut their throats 10 years before he had reformed his life, and then was arrested and came before the judge. If he says, "Yes, I raped those women and killed them three years ago, but I have reformed and I no longer rape women." The judge will say, "You are not before me for your good deeds. You are here to be sentenced for raping those women 10 years ago, so you will have to go to the electric chair."
But if a person from his youth was a lying, thieving, blaspheming, adulterer at heart, and comes to Christ by grace through faith alone in Him, will have all his past wiped out, and will repent and forsake those sins. But if he depends on good works as well as faith, God will still see him according to those sins in the same way as the judge sees the person is still a convicted rapist regardless of the good works he does afterward.
So a person who depends on his good works for salvation will be judged on his failure to keep the Ten Commandment perfectly from his youth up. And there will be no avoiding a guilty judgment and the subsequent penalty.
But when a person is depending on Christ's finished work through faith, he will still be found guilty at the judgment, but his debt of sin will be paid by Jesus and God's case against him will be dismissed and he will go free.
So, James teaches that the evidence that the person is forsaking his sinful acts and habit patterns, shows a genuine faith in Christ.