Charles Ellicott Commentary Acts 11:2

"And when Peter was come up to Jerusalem, they that were of the circumcision contended with him," — Acts 11:2 (ASV)

They that were of the circumcision contended with him.—The conversion of the Gentiles at Caesarea had given a new significance to the name of “those of the circumcision.” From this time onward they are a distinct section, often a distinct party, in the Church, and here we have the first symptom of the line which they were about to take. They contended with Peter (the tense implies continuous or repeated discussion) because he had eaten with those who were uncircumcised, and therefore, from the Jewish point of view, unclean.