I’m sure every church has their own doctrine, which is why it’s called denomination and what separates denominations is doctrine. That said, one does not need to read any commentary on James and it spells is out pretty clearly. James is not contrasting every law in scripture he very specifically is contrasting the Ten Commandments and comparing breaking one of the commandments is like breaking them all. This is an easy one….
James 2:10 For whoever shall keep the whole law, and yet stumble in one point, he is guilty of all. 11 For He who said, “Do not commit adultery,” also said, “Do not murder.” Now if you do not commit adultery, but you do murder, you have become a transgressor of the law. 12 So speak and so do as those who will be judged by the law of liberty.
James did not say if you are not circumcised, or not keeping the annual feast days and compares that to one of the Ten Commandments- He is contrasting the Ten Commandments and says if we break one we become the transgressor of the law, the Ten Commandments. He literally spelled it out. Also said its what we will be judged by, the law of liberty and if we keep the commandments we are free from the bondage of sin, which is breaking God’s law 1 John 3:4 and Paul points to the Ten to define sin. Romans 7:7 which is why the Ten Commandments are under Christs’ mercy seat in the Most Holy of His Temple, the commandments He personally wrote and placed in our hearts and minds, which we are grafted in through faith. Gal 3:26
It’s the whole law - the Ten James is quoting from. The Ten Commandments stand on a different foundation and sadly so many people have been deceived to think we do not need to keep God’s commandments. Paul say it’s what matters 1 Cor 7:19
Yes, the Royal Law or the Ten Commandments summed up is how to God and loving neighbor and is shown by keeping the Ten Commandments. The first 4 commandments deal with our relationship with God, the last 6 deal with our relationship with each other. Keeping the commandments of God is love to God and neighbor 1 John 3:4-5
No, the SDA church did not write James. We have to trust the scripture.