I’ve heard people say the book of James was written for the Jews. If so, how do we appropriate the verses on healing such as James 5:14-15 for ourselves, being gentiles? And if it’s not for the Church, why is it in the Bible?
The Epistle of James was written by the Lord’s half brother while he was the bishop of the Church in Jerusalem. There are different opinions as to exactly when he wrote the letter but the most likely date appears to be the late 40s AD, about 15 years after the cross. (He was killed in 62 AD so it had to have been written before then.)
During this time the Church was almost entirely made up of Jewish believers, so the fact that it was addressed to the 12 tribes is irrelevant.
James described himself as a servant of the Lord Jesus Christ (James 1:1) and identified his readers as believers in the Lord Jesus Christ as well (James 2:1). That made them all part of the Church. The fact that his letter is in the Bible means the early Church believed it was written to and for the Church and that James was writing to us under the inspiration of the Holy Spirit.