The book of James is considered to be the earliest writing in the NT, at a time when the believing assembly was totally Jewish and the believing Jews were still zealous of the law Act 21:20 and gentiles were not even under consideration.
Act 21:20 And when they heard it, they glorified the Lord, and said unto him, Thou seest, brother, how many thousands of Jews there are which believe; and they are all zealous of the law:
Act 10:28 And he said unto them, Ye know how that it is an unlawful thing for a man that is a Jew to keep company, or come unto one of another nation;
Act 11:2 And when Peter was come up to Jerusalem, they that were of the circumcision contended with him,
Act 11:3 Saying, Thou wentest in to men uncircumcised, and didst eat with them.
Act 11:19 Now they which were scattered abroad upon the persecution that arose about Stephen travelled as far as Phenice, and Cyprus, and Antioch, preaching the word to none but unto the Jews only.