What was a Grecian in the Bible?
A Grecian was a Jew who was a citizen of some other nation except Palestine, not a native of Palestine. A Greek, by contrast, is a Gentile. So Grecians were Jews, while Greeks were Gentiles—a distinction that marked a change in the audience being addressed.
Les explains that a Hellene was a Greek, and he notes that many good Bible scholars think the word here should be Greeks. A Grecian, however, was a Jew who was a citizen of some other nation except Palestine—a Jew who was not a native of Palestine. A Greek is a Gentile. Les says it would not have been unusual for Jewish believers to talk to fellow Jews, because that is what a Grecian was, but approaching Greeks was a change in venue and a complete change in modus operandi. They had not been talking to Greeks, but now they were. God had started moving toward the Gentile world when He saved Saul, then sped it up when He sent Peter to Cornelius. Now Saul had returned from three years of learning and the revelation of the mysteries, and the Gospel was going out to the Gentiles. These Jews who had preached to Jew only began speaking to Greeks and preaching the Lord Jesus. The hand of the Lord was with them, and a great number believed and turned to the Lord.