I’ll try to simplify things:
The scripture says “though a man may say” which specifically faith is not just a verbal aspect or a mental assent just like the devil v.19 which is to be contrasted to “the faith of Jesus” v.1. Real faith works. The core belief has nothing to do with faith and works to be saved. Works providing your brother with their needs when you are capable of doing so is to show you really are saved. Yes, this conduct of believers is seen by the Lord and it is one of the proofs we are saved. This work will actually complement and not contradict Paul’s justification which is an act of God to declare righteous. Whereas those justified by God will need to validate, give evidence, or “justify” through their works.
Fulfilling the “royal law according to the scripture” is to do well James 2:8 yet keeping the law is not God’s way to obtain the favor of God “For whosoever shall keep the whole law, and yet offend in one point, he is guilty of all” hence, this is not about faith +works = salvation. This merely shows, that saved “brethren” is to give evidence and not act like what the scripture said of a “vain man” v.20 who of course has his faith (verbal/mental) yet it’s dead.
Also, nothing in either James 1, or James 2 says that one is justified before men alone and not God. One is stretching the meaning of James 2:18 to say that when it simply not there in the verse. As I basically said before, you can read James 2:18 with being justified before God with no contradiction. Like I said back in post #1375, I have provided context that shows that James was talking in salvific terms that relates to our right standing with God and not men. This is clear if one just reads the text plainly like a child and they are not trying to insert OSAS or “Perpetual Belief Alone Salvationism” into the text.