Note 1 at Ac 11:2: This terminology, "of the circumcision," is always used to distinguish Jews. It refers back to the covenant of circumcision that God made with Abraham in Ge 17:9-14 and 23-27, and with all his seed. The term became synonymous with Jews in general and was used to distinguish the nation of Israel (Ro 2:25-26, 3:30, 4:9; and Ga 2:9).

In this instance, "of the circumcision" was referring to Jewish Christians. These people were born again, but they had not yet received the revelation that Christianity was different than Judaism and that people did not have to be circumcised to be saved.